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1
Axelsson, Mathias. "Transparent conductive oxides deposited by magnetron sputtering: synthesis and characterization." Thesis, Uppsala universitet, Fasta tillståndets elektronik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-390150.
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The thesis has dealt with transparent conducting oxide (TCO) materials, with a focus on Al:ZnO and with studies on Sn:In2O3 and ZnO. TCOs are a material group that is used for its properties of being conductive and at the same time transparent. In solar cells, a top layer of TCO is often used to allow light to transmit into the cell and then conduct the resulting current. A set of growth parameters was chosen and optimized through a literature study and experiments. The depositied thin films were characterized by optical and electrical characterization methods. Rf-magnetron-sputtering was used as the deposition method, where the influence of O2, argon and substrate temperature were the parameters to be studied. As a part of the characterization a model for spectroscopic ellipsometry on Al:ZnO was made, enabling faster measurement of transport properties. The main parameter affecting the TCO properties was found to be oxygen flow and the optimum flow value for each material has been determined. Substrate heating did not show any significant improvement on the resistivity of Al:ZnO with a minimum value of ~5.0*10-4 Ωcm while no heating resulted in a value of ~6.0*10-4 Ωcm. These values are comparable to the state-of-the-art from the literature. As a demonstration of application, the developed AZO and ZnO were applied to CIGS solar cells and these were compared to a reference. The newly developed AZO and ZnO was comparable to the reference but a lower mean fill factor indicates that improvements can be made.
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Zhang, Menglong. "Ordered transparent conductive oxides (TCOs) for applications to photoelectrochemistry." Thesis, University of York, 2016. http://etheses.whiterose.ac.uk/15194/.
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A method for fabricating high quality photonic TCO (transparent conductive oxide) films of macroporous FTO (fluorine doped tin oxide) (mac-FTO) and hollow sphere AZO (aluminum doped zinc oxide) (hs-AZO) is described. The films were used as electrodes to support photoelectrochemical reactions relevant to energy research. Methods have been developed for conformal coating the TCO electrodes with photoactive materials including CdS, Fe2O3 and C3N4. Previous literature describing photonic mac-FTO films generally show poor conductivity and optical properties, which limit the performance of structured TCOs in supporting photoelectrochemistry. Optimizing the synthesis and processing conditions gives high quality optical and conductive films of mac-FTO. Coating films with dispersed nanoparticles of CdS shows that the mac-FTO supports charge carrier transport to the contact and is not just a structural support for continuous conductive films of photoactive materials. Coating to maximise photocurrent gives over 9 mA cm-2 for conformally coated CdS@mac-FTO under visible light (> 420 nm) through a simple approach, showing an improvement in comparison to previous CdS literature work on structured electrodes. The new hs-AZO TCO also supports photocurrents up to 7.8 mA cm-2 after CdS coating. Both FTO and AZO show significant photocurrent enhancement in comparison to planar FTO analogues. In addition to CdS, methods were developed to conformally coat the organic photocatalyst C3N4 and the metal oxide Fe2O3 onto mac-FTO which showed enhanced photocurrent compared to planar analogues. Enhancements were typically in the range x (CdS), y (C3N4), and z (Fe2O3) which reflect the increase in surface area and greater loading of photoactive material. Potential photonic enhancements were not determined, however there is clearly scope for increasing the photocurrent per illuminated surface area using structured TCO electrodes.
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Song, Dengyuan Centre for Photovoltaic Engineering UNSW. "Zinc oxide TCOs (Transparent Conductive Oxides) and polycrystalline silicon thin-films for photovoltaic applications." Awarded by:University of New South Wales. Centre for Photovoltaic Engineering, 2005. http://handle.unsw.edu.au/1959.4/29371.
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Transparent conductive oxides (TCOs) and polycrystalline silicon (poly-Si) thin-films are very promising for application in photovoltaics. It is extremely challenging to develop cheap TCOs and poly-Si films to make photovoltaic devices. The aim of this thesis is to study sputtered aluminum-doped ZnO TCO and poly-Si films by solid-phase crystallization (SPC) for application in low-cost photovoltaics. The investigated aspects have been (i) to develop and characterize sputtered aluminum-doped ZnO (ZnO:Al) films that can be used as a TCO material on crystalline silicon solar cells, (ii) to explore the potential of the developed ZnO:Al films for application in ZnO:Al/c-Si heterojunction solar cells, (iii) to make and characterize poly-Si thin-films on different kinds of glass substrates by SPC using electron-beam evaporated amorphous silicon (a-Si) [referred to as EVA poly-Si material (SPC of evaporated a-Si)], and (iv) to fabricate EVA poly-Si thin-film solar cells on glass and improve the energy conversion efficiency of these cells by post-crystallization treatments. The ZnO:Al work in this thesis is focused on the correlation between film characteristics and deposition parameters, such as rf sputter power (Prf), working gas pressure (Pw), and substrate temperature (Tsub), to get a clear picture of film properties in the optimized conditions for application in photovoltaic devices. Especially the laterally non-uniform film properties resulting from the laterally inhomogeneous erosion of the target material are investigated in detail. The influence of Prf, Pw and Tsub on the structural, electrical, optical and surface morphology properties of ZnO:Al films is discussed. It is found that the lateral variations of the parameters of ZnO:Al films prepared by rf magnetron sputtering can be reduced to acceptable levels by optimising the deposition parameters. ZnO:Al/c-Si heterojunction solar cells are fabricated and characterized to demonstrate the feasibility of the fabricated ZnO:Al films for application in heterojunction solar cells. In this application, expensive indium-tin oxide (ITO) is usually used. Under the standard AM1.5G spectrum (100 mW/cm2, 25 ??C), the best fabricated cell shows an open-circuit voltage of 411 mV, a short-circuit current density of 30.0 mA/cm2, a fill factor of 66.7 %, and a conversion efficiency of 8.2 %. This is believed to be the highest stable efficiency ever reported for this type of cell. By means of dark forward current density-voltage-temperature (J-V-T) measurements, it is shown that the dominant current transport mechanism in the ZnO:Al/c-Si solar cells, in the intermediate forward bias voltage region, is trap-assisted multistep tunneling. EVA poly-Si thin-films are prepared on four types of glass substrates (planar and textured glass, both either bare or SiN-coated) based on evaporated Si, which is a cheaper Si deposition method than the existing technologies. The textured glass is realized by the UNSW-developed AIT process (AIT = aluminium-induced texture). The investigation is concentrated on finding optimized process parameters and evaluating film crystallization quality. It is found that EVA poly-Si films have a grain size in the range 0.8-1.5 ??m, and a preferential (111) orientation. UV reflectance and Raman spectroscopy measurements reveal a high crystalline material quality, both at the air-side surface and in the bulk. EVA cells are fabricated in both substrate and superstrate configuration. Special attention is paid to improving the Voc of the solar cells. For this purpose, after the SPC process, the samples receive the two post-crystallization treatments: (i) a rapid thermal anneal (RTA), and (ii) a plasma hydrogenation. It is found that two post-crystallization treatments more than double the 1-Sun Voc of the substrate-type cells. It is demonstrated that RTA improves the structural material quality of the cells. Furthermore, a hydrogenation step is shown to significantly improve the electronic material quality of the cells. Based on the RTA???d and hydrogenated EVA poly-Si material, the first mesa-type EVA cells are fabricated in substrate configuration, by using sputtered Al-doped ZnO as the transparent front contact. The investigation is focused on addressing the correlation between the type of the substrate and cell performance. Optical, electrical and photovoltaic properties of the devices are characterized. It is found that the performance of EVA cells depends on the glass substrate topography. For cells on textured glass, the AIT texture is shown to have a beneficial effect on the optical absorption of EVA films. It is demonstrated that a SiN barrier layer on the AIT-textured glass improves significantly both the crystalline quality of the poly-Si films and the energy conversion efficiency of the resulting solar cells. For cells on planar glass, a SiN film between the planar glass and the poly-Si film has no obvious effect on the cell properties. The investigations in this thesis clearly show that EVA poly-Si films are very promising for poly-Si thin-film solar cells on glass.
4
Morken, Michael Owen Morken. "An Investigation Into The Feasibility Of Transparent Conductive Coatings At Visimax Technologies." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1496835960043161.
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Heimke, Bruno. "RF überlagertes DC-Sputtern von transparenten leitfähigen Oxiden." Doctoral thesis, Universitätsbibliothek Chemnitz, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-116687.
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Die vorliegende Dissertation befasst sich mit dem RF- überlagerten DC-Sputtern von Indiumzinnoxid und aluminiumdotierten Zinkoxid. Bei dem dafür entwickelten synchron gepulsten RF/DC-Verfahren werden die zu untersuchenden Materialien gleichzeitig mit Hilfe eines RF- und eines PulsDC-Generators gesputtert.
Ein wesentliches Resultat der Untersuchungen ist, dass durch RF- überlagertes DCSputtern Schichten abgeschieden werden können, die im Vergleich zum DC- bzw. PulsDC-Sputtern geringere spezifische Widerstände aufweisen. Dies ist auf eine Verringerung von Defekten in den abgeschiedenen Schichten zurückzuführen. Es konnte anhand der Untersuchungen gezeigt werden, dass fur die Abscheidung von Indiumzinnoxid und aluminiumdotiertem Zinkoxid die Substrattemperatur beim RF überlagerten DC-Sputtern gegenüber dem DC-Sputtern um bis zu 100°C verringert werden kann.
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Heimke, Bruno. "RF überlagertes DC-Sputtern von transparenten leitfähigen Oxiden." Doctoral thesis, Universitätsverlag der Technischen Universität Chemnitz, 2012. https://monarch.qucosa.de/id/qucosa%3A19919.
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Die vorliegende Dissertation befasst sich mit dem RF- überlagerten DC-Sputtern von Indiumzinnoxid und aluminiumdotierten Zinkoxid. Bei dem dafür entwickelten synchron gepulsten RF/DC-Verfahren werden die zu untersuchenden Materialien gleichzeitig mit Hilfe eines RF- und eines PulsDC-Generators gesputtert.
Ein wesentliches Resultat der Untersuchungen ist, dass durch RF- überlagertes DCSputtern Schichten abgeschieden werden können, die im Vergleich zum DC- bzw. PulsDC-Sputtern geringere spezifische Widerstände aufweisen. Dies ist auf eine Verringerung von Defekten in den abgeschiedenen Schichten zurückzuführen. Es konnte anhand der Untersuchungen gezeigt werden, dass fur die Abscheidung von Indiumzinnoxid und aluminiumdotiertem Zinkoxid die Substrattemperatur beim RF überlagerten DC-Sputtern gegenüber dem DC-Sputtern um bis zu 100°C verringert werden kann.
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Sasi, Abdalla Suliman. "Energy efficiency of solar heat concentrators using glass coated Al doped ZnO transparent conducting oxide as selective absorber." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2699.
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Thesis (Master of Engineering in Mechanical Engineering)--Cape Peninsula University of Technology, 2017.Transparent conductive oxides (TCOs), which are widely used in transparent electronics, possess a spectral selectivity that is suitable for a solar material absorber. TCO materials have a plasma wavelength in the infrared region. Consequently electromagnetic waves shorter than a plasma wavelength are transmitted through the material, while longer electromagnetic waves are reflected on the surface. In contrast to the opaque solar selective absorbers, the plasma wavelength in TCO materials can be easily tuned by controlling the heavy doping process to match the peak shift of thermal radiation at higher temperatures. Furthermore, the use of TCO in conjunction with a solar absorber relaxes the spectral selectivity of the latter and thus widens the selection of the solar absorber; subsequently the only requirement is a thermally stable black body. Aluminum doped Zinc Oxide (AZO) is a class of TCO materials which is cost effective to manufacture due to abundance ZnO, and Aluminum raw materials. This thesis is based on the synthesis of Al doped ZnO thin films nanostructure using radio frequency RF magnetron sputtering process. The influence of the deposition parameters, including argon working pressure and substrate temperature, on the structural and optical properties of the AZO thin films is investigated by means of X-ray diffraction (XRD) and optical spectroscopy (UV-VIS-NIR). The optical constants of AZO films are extracted from transmittance and reflectance spectra using a combination of Drude and Lorentz dielectric function model. A computer simulation is developed to calculate the radiative properties of Al doped ZnO thin films nanostructure. The thermal emittance and solar absorptance is predicted indirectly from optical reflectance and transmittance of AZO films by invoking Kirchhoff’s law. A Special attention has been paid to the parameters that influence the spectral properties of the AZO films including carrier’s mobility, Al doping concentration and film thickness. Carrier’s mobility turned out to have the most significant influence on the spectrally selective performance of AZO films.
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Mavlonov, Abdurashid. "Doping Efficiency and Limits in Wurtzite (Mg,Zn)O Alloys." Doctoral thesis, Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-214372.
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In this thesis, the structural, optical, and electrical properties of wurtzite MgxZn1-xO:Al and MgxZn1-xO:Ga thin films have been investigated in dependence on Mg and dopant concentration. Among the transparent conductive oxides (TCOs), ZnO based compounds have gained renewed interest as a transparent electrode for large scale applications such as defroster windows, at panel displays, touch screens, and thin film solar
cells due to low material and processing cost, non-toxicity, and suitable physical properties. In general, these applications require transparent electrodes with lowest possible resistivity of rho < 10^-3 Ohmcm and lower [1]. Recently, it has been reported that Ga and Al doped ZnO thin films can be deposited with respective resistivity of 5x10^-5 Ohmcm [2] and 3 x10^-5 Ohmcm [3] which are similar to the data obtained for other practical TCOs, i.e. the resistivity of about 4x 10^-5 Ohmcm for Sn doped In2O3 (ITO) thin films [4]. Moreover, the bandgap of ZnO can be increased by alloying with Mg offering band alignment between transparent electrode and active (or buffer) layer of the device, e.g. Cu(In,Ga)Se2 solar cells [5]. The tunable bandgap of these transparent electrodes can further increase the efficiency of the devices by avoiding energy losses in the interface region of the layers. From this point of view, this work has been aimed to investigate the doping efficiency and limits in transparent conductive (Mg,Zn)O alloys. For this purpose, the samples investigated in this work have been grown by pulsed-laser deposition (PLD) using a novel, continuous composition spread method (CCS). In general, this method allows to grow thin films with lateral composition gradient(s) [6, 7]. All MgxZn1-xO:Al and MgxZn1-xO:Ga thin films have been deposited on 2-inch in diameter glass, c- or r-plane sapphire substrates using threefold segmented PLD targets in order to grow thin films with two perpendicular, lateral composition gradients, i.e. the Mg composition is varied in one direction whereas the Al/Ga concentration is varied in a perpendicular direction [7, 8]. In order to investigate the influence of the temperature, samples grown at different substrate temperatures in the range of 25 to 600 C were investigated. The
optical and electrical measurements have been carried out on (5x 5)mm^2 samples that were cut from the CCS wafers along the respective composition gradients, i.e. Mg and Al/Ga contents. Subsequently, physical properties of thin films have been analyzed for a large range of Al/Ga content between 0.5 and 7 at.%, which corresponds to doping
concentrations between 2x 10^20 and 3x 10^21 cm^-3, for different Mg contents x(Mg) ranging from 0.01 to 0.1.
It has been found that practically the limiting the dopant concentrations is about 2 x10^21 cm^-3. Further, the electrical data suggests, that the compensating intrinsic defect is doubly chargeable hinting to the zinc vacancy (V_Zn) as microscopic origin. Increasing the dopant concentration above 2 x10^21 cm^-3 leads to a degradation of electrical and
structural properties [8].
Further, the influence of growth and annealing temperatures on structural, electrical and optical properties of the films has been studied. For that purpose, Al and Ga doped (2.5 at.% = 1x10^21 cm^-3) Mg0.05Zn0.95O thin films have been chosen from CCS samples grown at T_g = (25 - 600) C . For both doping series, the samples grown at higher temperatures exhibit better crystalline quality compared to the samples grown at lower growth temperatures. As a result, samples grown at higher temperatures reveal
higher Hall mobility. For the Al-doping series, the highest free charge carrier density of n = 8.2x 10^20 cm^-3 was obtained for an Mg0.05Zn0.95O:Al thin film grown at 200 C, with corresponding Hall mobility of mu = 13.3 cm^2/Vs, a resistivity of rho = 5.7x10^-4 Ohmcm,
and optical bandgap of E_g = 3.8 eV. Interestingly, the free charge carrier density of n = (5 - 8) x 10^20 cm^-3 for samples grown with T_g > 300 C is clearly higher than the value of n = 1.25 x 10^20 cm^-3 that was obtained for the high temperature grown sample, i.e. at T_g = 600 C. Furthermore, for all T_g, Al-doped films have a higher doping efficiency than the Ga-doped counterparts. In order to look deeper into the microscopic origin of this behavior, the samples were post-annealed in vacuum at 400 C.
Experimental results showed that the free charge carrier density of Al-doped samples first decreased and saturated afterward with increasing annealing time. On the other hand, the free charge carrier density of the Ga-doped samples first slightly increased and saturated with increasing annealing time. For both doping series, the saturation value of n ~ 1 x 10^20 cm^-3 was very close to the data that has been observed for (i) high temperature grown samples and (ii) the solubility limit of Al in ZnO of 0.3 at.% =
1.2x 10^20 cm^-3, that has been determined by Shirouzu et al. for high temperature grown (T_g > 600 C) Al-doped ZnO [9]. Correspondingly, the optical bandgap also changed, i.e. increased (decreased) for Al- (Ga-) doping series, and approached a constant value of 3.5 0 +- 0.1 eV which is explained by generation of acceptor-like compensating defects, and
the solubility limit of the dopants. From XRD data, no secondary phases were found for as-grown and post-annealed films. However, the slight improvement of crystalline quality has been observed on post-annealed samples. Further, it has been shown that the growth and annealing temperatures are important as they strongly affect the metastable state of
the solid solution that samples grown at low temperature represent. The low solubility limit of the dopants, i.e. 0.3 at.% for Al in ZnO under equilibrium condition, can be increased by preparing samples by non-equilibrium growth techniques [10]. This is also consistent with experimental results of this work that Al- as well as Ga-doped metastable ZnO and (Mg,Zn)O thin films can be prepared with highest possible doping efficiency for the dopant concentration up to 2.5 at.% when growth or annealing temperatures
below 400 C are used.
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Cheikh, Aimane. "Etudes des hétérostructures à bases d'oxydes complexes pour de potentielles utilisations en cellules solaires." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMC208.
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Grace à leurs propriétés fonctionnelles prometteuses, l’étude des oxydes ternaires à base de vanadium déposés sous forme de couche mince ont suscité beaucoup d’intérêt et ont fait l’objet d’une activité intense en recherche dans le domaine optoélectronique et photovoltaïque.Durant ce travail de thèse, on a étudié dans un premier temps la possibilité d’utiliser les métaux fortement corrélés tel que SrVO3 comme étant un oxyde transparent et conducteur (TCO). Pour cela, on a étudié l’évolution des propriétés optoélectroniques en fonction des conditions de croissance du SrVO3 déposé sous forme de couche mince. Dans un deuxième temps, notre étude s’est focalisée sur la réalisation d’une ingénierie de cellule solaire basée sur les hétérostructures tout oxyde de différentes bandes interdites. Pour cela, par un choix judicieux de la largeur de bande interdite de certaines pérovskites, nous avons synthétisé le LaVO3, dont l’absorption est optimale dans le spectre solaire, sur un substrat SrTiO3 sous différentes conditions de croissance. Du point de vue optique, l’étude des hétérostructures LaVO3/SrTiO3 déposé à basse pression d’oxygène a mis en évidence que le film LaVO3 possède une bande interdite de 1.18 eV se situant dans la plage optimale pour le photovoltaïque. Du point de vue électrique, l’interface polaire LaVO3/ SrTiO3 génère une couche d’interface conductrice qui servira de contact électrique pour les cellules solaires. Un autre intérêt du LaVO3 est sa structure cristalline commune à un grand nombre d’oxydes possédant des différentes valeurs des bandes interdites. Pour réaliser notre système, nous avons choisi en particulier la pérovskite LaFeO3 ayant une bande interdite de 2.2 eV, supérieure à celle du LaVO3 afin d’améliorer l’absorption optique à haute énergie. Une fois les propriétés optoélectroniques ont été établies, nous avons synthétisé l’empilement LFO/LVO sur un substrat SrTiO3 à basse pression d’oxygène. L’évolution des propriétés de notre système en fonction de l’épaisseur de LaFeO3 déposé est également étudié, mais jusqu’à présent aucune propriété de photoconductivité n’a été obtenueDue to their promising functional properties, ternary oxide thin films based on Vanadium have gained much research interest in photovoltaic technologies.During this work, we first studied the possibility to use the strongly correlated metal SrVO3 as a transparent conducting oxide (TCO). For this reason, we have studied the optoelectronic properties of SrVO3 under different growth conditions. Second, our study was focused on making band gap-graded design solar cells based on oxide heterostructures. LaVO3 is particularly interesting due to its optical band gap localized in the optimal range for harvesting solar light. Accordingly, the LaVO3 was synthetized on SrTiO3 substrate under different growth conditions. Optical measurements reveal that LaVO3/SrTiO3 heterostructure grown at low oxygen pressure possess a band gap of 1.18 eV in the ideal energy range for photovoltaic. Electrical properties show that the interface LaVO3/ SrTiO3 is conducting, serving as an electrical contact for solar cells. Another interest of LaVO3 is its crystalline structure offering the possibility to combine it with other structurally compatible transition metal oxides with larger band gap such as LaFeO3 (2.2 eV) in order to enhance the optical absorption at high energy. Once the optoelectronic properties have been established, the LFO/LVO heterostructure was synthetized on SrTiO3 substrate at low oxygen pressure. The physical properties of our system have been also investigated for different LaFeO3 thickness but, to date, no photoconductivity was obtained
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Giangolini, Matteo. "Production and characterization of tin oxide thin films deposited via solution combustion synthesis." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15816/.
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The main goal of this thesis work is the production and characterization of Tin oxide thin film deposited via Solution Combustion Synthesis (SCS). Different precursors are used in order to study the effect of the chemical nature of the reagent on the structural, morphological and electrical properties of the thin films.
Tin oxide was chosen because is one of the most promising candidates for p-type oxide. In fact, the semiconductor oxides reported in the literature are mostly limited to n-type and there is a need for solution processed p-type oxide semiconductors to achieve Complementary Metal Oxide Semiconductors (CMOS) using all oxide materials. Anyway, the production window of solution processed for p-type SnO is narrow and Silver doping will be used to enhance the probability to get it. If production of p-type Tin oxide will not be achieved, the work will be focused on n-type SnO2 and on the optimisation of devices made with this material, either Thin Film Transistors (TFTs) or Transparent Conductive Oxides (TCOs).
Samples made in this work show good optical properties, like transmittance over 80% and energy gap values around 3.79 eV, but none of them turned out to be a p-type oxide or a good TFT. Samples annealed at higher temperatures have good electrical conductivity properties, which could lead to a future study in order to optimise these materials for TCO purposes.
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Isherwood, Patrick J. M. "Development of transparent conducting oxides for photovoltaic applications." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/18886.
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Metal oxides are a very important class of materials with a wide range of photovoltaic applications. Transparent conducting oxides (TCOs) are the primary front contact materials used in thin film solar cells. Identification of methods for reducing the resistivity of these materials would have significant benefits. Development of p-type TCOs would provide alternative back contact materials and could enable further development of technologies such as bifacial, window and multijunction cells. A series of studies into these areas is presented in this work. Aluminium doped zinc oxide (AZO) is a well-known n-type TCO consisting entirely of Earth-abundant materials. Targets were manufactured from AZO powder, which was synthesised using a patented emulsion detonation process developed by Innovnano S.A. All films showed good optical transmission. Resistivity was found to decrease with both increasing time and temperature up to 300 degree C. Temperatures above 300 degree C were found to be detrimental to film formation, with increasing amounts of damage to the crystal structure and consequent increases in the resistivity. The effect of alloying molybdenum oxide with molybdenum nitride through reactive sputtering in a mixed oxygen-nitrogen atmosphere was investigated. All alloys were found to show p-type behaviour. Resistivity was found to improve with increased nitrogen content, in contrast to optical transmission, which reduced. A selection of compositions were deposited onto CdTe cells as back contacts. These cells showed an increase in efficiency with increasing nitrogen content. Work function was found to increase with increasing oxygen content, but all work functions were low. Resistivity was shown to correlate strongly with efficiency, caused by a corresponding increase in cell voltage. This implies that to form an ohmic contact on CdTe with p-type materials, work function may be less important than resistivity. The copper oxides are p-type, but uses are limited by the narrow band gaps. Cupric oxide was chosen for investigation and for alloying with other oxides with the aim of increasing the band gap. It was found that temperature and deposition environment have significant impacts on sputtered cupric oxide (CuO) films, with low temperatures and high oxygen environments producing the lowest resistivities. Extrinsic sodium doping was found to reduce the resistivity by up to four orders of magnitude. High oxygen content sodium-doped films were found to have carrier concentrations two orders of magnitude higher than that of indium tin oxide.
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Mei, Jun S. B. Massachusetts Institute of Technology. "Photoluminescence quenching of organic thin films by transparent conductive oxides." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35059.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006.Includes bibliographical references (p. 83-86).
One fundamental challenge in designing organic light-emitting diodes is luminescence quenching near an electrode. In this work, we investigate the underlying mechanism behind luminescence quenching by measuring the reduction in Alq3 photoluminescence due to SnO02. Using an analytical model and a Monte Carlo simulation for exciton dynamics in amorphous organic solids, we find that the exciton diffusion length in bulk Alq3 is in the range of 70--80 A. We also find that for SnO2 films deposited without oxygen in the sputtering ambient, resonant energy transfer from Alq3 to SnO2 is the dominant quenching mechanism. By varying the oxygen content in the Ar/C)2 sputtering gas mixture, we find that the energy transfer distance decreases from 10--25 A for 0% 02 to less than 2 A for 10% 02. Our experimental results suggest that because excess oxygen reduces oxygen vacancies and defect electronic states in SnO2, it leads to a smaller spectral overlap between the emission of Alq3 and the absorption of SnO2, thereby shortening the energy transfer distance and reducing the quenching capability of SnO2.
by Jun Mei.
S.B.
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Lemire, Heather M. "Degradation of Transparent Conductive Oxides: Mechanistic Insights and Interfacial Engineering." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1386325661.
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Kainikkara, Vatakketath Rithwik. "Investigation of the Transparent Conducting Oxide (TCO) material used in CIGS thin film solar cell in Midsummer AB." Thesis, Uppsala universitet, Institutionen för elektroteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-423109.
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Hammarberg, Elin [Verfasser], and C. [Akademischer Betreuer] Feldmann. "Nanoscale Transparent Conductive Oxides via Microwave-assisted Polyol Synthesis / Elin Hammarberg. Betreuer: C. Feldmann." Karlsruhe : KIT-Bibliothek, 2008. http://d-nb.info/1013696018/34.
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Tutsch, Leonard Verfasser], and Stefan [Akademischer Betreuer] [Glunz. "Implementing sputter-deposited transparent conductive metal oxides into passivating contacts for silicon solar cells." Freiburg : Universität, 2020. http://d-nb.info/1223849201/34.
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Tutsch, Leonard [Verfasser], and Stefan [Akademischer Betreuer] Glunz. "Implementing sputter-deposited transparent conductive metal oxides into passivating contacts for silicon solar cells." Freiburg : Universität, 2020. http://d-nb.info/1223849201/34.
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Boltz, Janika [Verfasser]. "Sputtered tin oxide and titanium oxide thin films as alternative transparent conductive oxides / Janika Boltz." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2012. http://d-nb.info/1019850485/34.
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Sechogela, Thulaganyo P. "Vanadium dioxide nanocomposite thin film embedded in zinc oxide matrix as tunable transparent conductive oxide." Thesis, University of the Western Cape, 2013. http://hdl.handle.net/11394/4529.
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Philosophiae Doctor - PhDThis project is aimed at fabricating a smart material. Zinc oxide and vanadium dioxide have received a great deal of attention in recent years because they are used in various applications. ZnO semiconductor in particular has a potential application in optoelectronic devices such as light emitting diodes (LED), sensors and in photovoltaic cell industry as a transparent electrode. VO2 also has found application in smart windows, solar technology and infrared smart devices. Hence the need to synthesis or fabricate a new smart material using VO2 and an active ZnO based nano-composites family in which ZnO matrix will be hosting thermally active VO2 nano-crystals is the basis of this study. Since VO2 behave as an MIT Mott’s type oxides and exhibits a thermally driven semiconductor-metal phase transition at about 68 oC and as a direct result ZnO:VO2 nano-composites would exhibit a reversible and modulated optical transmission in the infra-red (IR) while maintaining a constant optical transmission in the UV-Vis range. The synthesis is possible by pulsed laser deposition and ion implantation. Synthesis by pulsed laser deposition will involve thin films multilayer fabrication. ZnO buffer layer thin film will be deposited on the glass and ZnO single crystals and subsequent layer of VO2 and ZnO will be deposited on the substrate. X-ray diffraction (XRD) reveals that the series of ZnO thin films deposited by Pulsed Laser Deposition (PLD) on glass substrates has the hexagonal wurtzite structure with a c-axis preferential orientation. In addition the XRD results registered for VO2 samples indicate that all thin films exhibits a monoclinic VO2 (M) phase. UV-Vis NIR measurements of multilayered structures showed the optical tunability at the near-IR region and an enhanced transparency (>30 %) at the visible range.
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Yavas, Hakan. "Development Of Indium Tin Oxide (ito) Nanoparticle Incorporated Transparent Conductive Oxide Thin Films." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614475/index.pdf.
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Indium tin oxide (ITO) thin films have been used as transparent electrodes in many technological applications such as display panels, solar cells, touch screens and electrochromic devices. Commercial grade ITO thin films are usually deposited by sputtering. Solution-based coating methods, such as sol-gel however, can be simple and economic alternative method for obtaining oxide films and also ITO. In this thesis, &ldquoITO sols&rdquo
and &ldquo
ITO nanoparticle-incorporated hybrid ITO coating sols&rdquo
were prepared using indium chloride (InCl3
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Wei, Shijun. "Flame-made Nb-doped TiO2 Thin Films for Application in Transparent Conductive Oxides." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1447071519.
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Hsiao, Shih-Hsiu. "Ion Beam Modification of Thin Film Barrier Layer and Deposition of Transparent Conductive Oxides on Polymer Substrate for Flexible Display." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/57295.
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Shang, Congcong. "Synthesis of ruthenium-phosphorus dyes and their incorporation in ZnO transparent conducting oxide and ZnO semi-conductor thin films for photovoltaic application." Toulouse 3, 2013. http://thesesups.ups-tlse.fr/2265/.
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Cette thèse est consacrée au développement de nouveaux colorants moléculaires a base de complexes de ruthénium phosphorés, d'oxydes conducteurs transparents (TCO) et de matériaux semi-conduteurs (SC) à base de ZnO en vue de leur application dans des cellules solaires à colorants. Des voies synthétiques originales ont été développées pour la préparation de complexes symétriques et non symétriques de type ligands phosphorés fonctionnalisés. Les résultats obtenus souligne le rôle prépondérant des ligands phosphorés dans le contrôle des propriétés électroniques et optiques de ces colorants. Nous avons aussi étudié ZnO sous forme de films minces. En ciblant une interface TCO/SC homogène, des TCO à base d'oxyde de zinc dopés au Ga (ZnO:Ga) et des SC à base d'oxyde de zinc pur ont été déposés par pulvérisation cathodique radiofréquence à partir de cibles céramiques. Les microstructures et les propriétés physiques de ces matériaux ont été étudiées. Les conditions de dépôts ont été optimisées pour préparer des films minces TCO de ZnO:Ga présentant une grande transparence optique et de bonnes conductivités électroniques et des films minces SC à grande surface. La surface accessible des films minces ZnO a ensuite été améliorée par attaque chimique humide. Dans la dernière partie, nous avons associé les colorants moléculaires aux matériaux SC et TCO par greffage chimique. Des nanopoudres de ZnO ont été élaborées pour effectuer des tests de greffage avant leurs validations sur les matériaux en couche mince. Le colorant est ancré sur ZnO par les fonctions phosphorées. L'intégration de ces matériaux dans des cellules photovoltaïques à colorant sera l'objet de développements futursIn this work, we studied the development of new molecular ruthenium-phosphorus dyes and new Transparent Conducting Oxide (TCO) and ZnO Semi-Conductor (SC) materials in view of integrating them in dye sensitized solar cells. This thesis described first the original synthetic pathways that were developed to prepare both symmetrical and non-symmetrical complexes [Ru(bpy)2LL']n+ (L, L' : functionalized phosphorus ligands). Results highlight the predominant role of the phosphorus ligands in tuning the electronic and optical properties of the corresponding dyes. Secondly, we studied the preparation of new ZnO materials. In the goal of obtaining a homogeneous TCO/SC interface, zinc oxide doped Ga (ZnO:Ga) TCO and zinc oxide SC thin films were deposited by RF magnetron sputtering using ceramic targets. The microstructure and physical properties of these materials were studied. The deposition conditions were specifically optimized to prepare dense ZnO:Ga thin films with high transparency and good electrical conductivity for the TCO layer on one hand, and porous ZnO with high accessible surface for the SC layer on the other hand. The accessible surface of relatively porous ZnO thin films were further extended by post-deposition wet chemical etching. Finally, we associated the molecular dyes to the SC and the TCO materials by chemical grafting. Preliminary grafting tests were first investigated on homemade ZnO nanopowders before being validated on thin film materials. In these new materials, the dye is anchored to the ZnO through phosphorus functionalized functions. As a continuation of this work, the integration of these new materials in DSSCs will be the focus of further studies
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Liu, Qiudi. "Optimization and Characterization of Transparent Oxide Layers for CIGS solar cells fabrication." Connect to full text in OhioLINK ETD Center, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1187376131.
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Thesis (M.S.)--University of Toledo, 2007.Typescript. "Submitted as partial fulfillment of the requirements for the Masters of Science Degree in Physics." "A thesis entitled"--at head of title. Bibliography: leaves 99-102.
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Popescu, Andrei. "Laser deposition and characterization of transparent conductive, bioactive, hydrophobic and antiseptic nanostructures." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4016.
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Les applications présentées dans cette thèse valorisent de diverses manières le principe d'ablation laser, c'est à dire l'arrachement de la matière d'une surface solide suite à l'irradiation avec un faisceau laser. Le plasma généré par irradiation laser impulsionnel a été utilisé pour le dépôt de couches minces ou de nanoparticules et pour l'analyse compositionnelle des couches d'épaisseur nanométrique. Nous avons synthétisé par dépôt laser combinatoire des librairies compositionnelles d'un oxyde mixte transparent d'In et Zn. En utilisant le plasma d'ablation pour le diagnostic compositionnel, nous avons déterminé les concentrations d'indium et de zinc dans les couches minces par spectroscopie laser. Des couches minces de bioverre ont été synthétisées par dépôt laser impulsionnel sur des substrats de titane. En contact avec des cellules ostéoblastes, les bioverres ont stimulé la prolifération et ont augmenté la viabilité. La prolifération des ostéoblastes cultivés sur les couches de bioverre a été 30% supérieure a l'échantillon de contrôle. On a déposé par PLD des couches minces ou nanoparticules adhérentes de ZnO sur des substrats textiles hydrophiles dans un flux d'oxygène ou sous vide pour obtenir des structures avec différentes mouillabilités. En augmentant le nombre d'impulsions laser de 10 à 100 nous avons observé la transition du recouvrement par des nanoparticules isolées vers des couches minces. En fonction de l'atmosphère environnant lors du dépôt, les couches minces et les nanoparticules ont changé leur mouillabilité, passant d'hydrophile en flux d'oxygène à un comportement superhydrophobe (angle de contact de 157°) en cas de dépôt sous videThe applications presented in this thesis exploit in different modes the principle of laser ablation, i.e. the material removal from a solid surface following irradiation with a pulsed laser beam. The plasma generated by laser ablation was used for thin films or nanoparticles deposition and for the compositional analysis of nanometric thin films. We synthesized by combinatorial pulsed laser deposition, thin film libraries of a complex oxide of In and Zn. Using the ablation plasma for compositional diagnostic, we determined the In and Zn concentrations in films by Laser Induced Breakdown Spectroscopy using a procedure based on the spectral luminance calculation of a plasma in local thermodynamic equilibrium. Thin films of bioactive glass were synthesized by pulsed laser deposition, magnetron sputtering and MAPLE on Ti substrates and tested the transfer accuracy by physico-chemical tests and their functionality in vitro. In contact with human osteoblast cells, the bioactive glasses stimulated their proliferation and enhanced their viability. The proliferation of osteoblasts cultivated on bioactive films was 30% superior to the control sample. ZnO thin films or nanoparticles were deposited on hydrophilic textile substrates in oxygen flux or in vacuum in order to obtain structures with different wetting behavior. Increasing the number of laser pulses from 10 to 100, we observed a coating transition from isolated nanoparticles to thin films fully coating the textile fibers. Function of the ambient atmosphere during experiments, the structures changed their wetting behavior, passing from hydrophilic in oxygen flux to superhydrophobic (157°) in case of deposition in vacuum
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Götzendörfer, Stefan [Verfasser], and Peer [Akademischer Betreuer] Löbmann. "Synthesis of Copper-Based Transparent Conductive Oxides with Delafossite Structure via Sol-Gel Processing / Stefan Götzendörfer. Betreuer: Peer Löbmann." Würzburg : Universitätsbibliothek der Universität Würzburg, 2011. http://d-nb.info/1015500552/34.
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Nebatti, Ech-Chergui Abdelkader [Verfasser], Burak [Akademischer Betreuer] Atakan, and Volker [Akademischer Betreuer] Buck. "Functional doped metal oxide films : [[Elektronische Ressource]] : Zinc oxide (ZnO) as transparent conducting oxide (TCO) Titanium dioxide (TiO2) as thermographic phosphor and protective coating / Abdelkader Nebatti Ech-Chergui. Gutachter: Volker Buck. Betreuer: Burak Atakan." Duisburg, 2011. http://d-nb.info/1015428088/34.
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Santos, Irajan Moreira. "Estudo das propriedades estruturais, óticas e elétricas de filmes finos de Zno dopados com Al e Cr." Pós-Graduação em Física, 2018. http://ri.ufs.br/jspui/handle/riufs/9116.
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Fundação de Apoio a Pesquisa e à Inovação Tecnológica do Estado de Sergipe - FAPITEC/SEIn this work, we analyze the structural, optical and electrical properties of thin films of ZnO - doped with aluminum (Al) and chromium (Cr), with concentrations of 3%, grown by non - reactive magnetron sputtering. The samples were grown using glass as substrates. For the production of the capacitors used in the electric characterization an Al layer was grown on the substrate which was used as the lower electrode. The films studied here were obtained by varying the thickness and temperature of the substrate, between ambient temperature and 400 ° C. The films obtained were characterized by X-ray diffraction (XRD), X-ray reflectometry (XRR), optical spectroscopy in the UV-Vis region, and IxV voltage current plotes. The results showed that the films produced have a large preferential orientation with planes (002) of the ZnO wurtzite hexagonal phase perpendicular to the surface of the substrate. By means of the XRR measurements, the experimental thicknesses were obtained as well as the roughness and mass density of the films. From the UV-Vis measurements, it was observed that the films have a high transmittance (above 80%) with a slight reduction with increasing thickness. The measurements of the IxV curves showed that the films have an ohmic behavior with a low resistance and resistivity, therefore possessing compatible properties to be used with conductive oxides and transparent for both dopants. The bandgap values for all films are close to 3.3 eV without significant variation with the parameters used.
Neste trabalho, são apresentadas discussões sobre as propriedades estruturais, óticas e elétricas de filmes finos de ZnO — dopado com alumínio (Al) e cromo (Cr), com concentrações de 3%, crescidos por pulverização catódica não reativa. As amostras foram crescidas utilizando vidro como substratos. Para a produção dos capacitores utilizados na caracterização elétrica foi crescido uma camada de Al sobre o substrato que foi utilizado como eletrodo inferior. Os filmes aqui estudados foram obtidos variando a espessura e a temperatura do substrato, entre temperatura ambiente e 400 °C. Os filmes obtidos foram caracterizados pelas técnicas de difração de raios X (DRX), reflectometria de raios X (XRR), espectroscopia óptica na região do UV-Vis e curvas de corrente por tensão IxV. Os resultados mostraram que os filmes produzidos possuem uma grande orientação preferencial com planos (002) da fase hexagonal wurtzita do ZnO perpendicular à superfície do substrato. Por meio das medidas de XRR, foram obtidas as espessuras experimentais assim como a rugosidade e densidade de massa dos filmes. A partir das medidas de UV-Vis, foi observado que os filmes possuem uma alta transmitância (acima de 80%) com uma leve redução com o aumento da espessura. As medidas das curvas IxV mostraram que os filmes apresentam um comportamento ôhmico com uma baixa resistência e resistividade, possuindo, portanto, propriedades compatíveis para serem utilizados como óxido condutore e transparente para ambos os dopantes. Os valores do bandgap para todos os filmes são próximos de 3,3 eV sem variação significativa com os parâmetros utilizados.
São Cristóvão, SE
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Molloy, James. "Argon and argon-chlorine plasma reactive ion etching and surface modification of transparent conductive tin oxide thin films for high resolution flat panel display electrode matrices." Thesis, University of Ulster, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243741.
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Balestrieri, Matteo. "Transparent conductive oxides with photon converting properties in view of photovoltaic applications : the cases of rare earth-doped zinc oxide and cerium oxide." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAE019/document.
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L’objectif de cette thèse était d’étudier les propriétés de conversion de photons des ions terres rares insérées dans des matrices d’oxydes transparents en vue d’application photovoltaïques. En particulier, le but était de fonctionnaliser des couches minces déjà utilisées dans les cellules solaires comme couches antireflet ou oxydes transparents conducteurs. Nous avons donc sélectionné deux matériaux (ZnO et CeO2) compatibles avec les cellules solaires au silicium.Ce travail a montré que les couches minces dopes aux terres rares peuvent être utilisées pour convertir les photons dans des applications photovoltaïques, mais qu’il n’est pas facile d’obtenir des rendements élevés.Cependant, nous avons obtenu des informations très importantes sur l’influence de la matrice sur les propriétés de conversion des terres rares et sur les mécanismes de transfert d’énergie entre la matrice et la terre rareThe objective of this thesis was to investigate the photon converting properties of rare earths (RE) ions embedded in transparent oxide hosts in view of potential application on silicon solar cells. In particular, the goal was to functionalize thin films that are already used in solar cells such as anti-Reflection coatings or transparent conductive oxides.Two host materials (ZnO and CeO2) have been selected, which are compatible with silicon solar cells.This work shows that RE-Doped transparent oxide films are a viable low-Cost solution for obtaining photon-Converting layers that can be applied on solar cells, but that achieving high efficiencies is much more difficult than it might appear in theory. Nevertheless, very valuable information has been obtained on the effect of the host material on the photon management properties and on the energy transfer mechanisms in these systems. In particular, the energy level diagram of some of the rare earth ions in the specific matrices has been reconstructed
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Carreras, Seguí Paz. "Doped and multi-compound ZnO-based transparent conducting oxides for silicon thin film solar cells." Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/109157.
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The objective of the present work is to provide a better understanding of magnetron sputtered transparent conducting oxides based on ZnO in order to use them as electrodes in thin film silicon solar cells at the Grup d'Energia Solar of the Universitat de Barcelona. This thesis presents the properties of magnetron sputtered aluminium and gallium doped ZnO as well as the properties of multi-compound materials deposited by the co-sputtering of zinc oxide and indium tin oxide. The application of ZnO based transparent conducting oxides to the back reflector of pin amorphous solar cells is also discussed.
A set of aluminium doped zinc oxide layers were deposited under different substrate temperature and discharge power. The structural, electrical and optical properties were characterised and discussed. The higher substrate temperatures and discharge powers used during deposition led to highly transparent layers in the visible range with lower resistivities. The polycrystalline layers were oriented with the c-axis perpendicular to the substrate surface and the crystalline quality of the layers improved at higher temperatures and powers. A remarkable increase in mobility was found for temperatures above 300°C and the carrier concentration also rose with temperature reaching 3.71x1020 cm-3 at 420°C. The most remarkable feature found at higher deposition power was the increase in deposition rate (from 0.9 to 9 nm/min).
By means of a high temperature (650°C) annealing process under a capping layer of silicon or alumina, the mobility of aluminium doped zinc oxide layers was considerably raised achieving 68.5 cm2V-1s-1. This process led also to more transparent layers in the near infrared as well as in the ultraviolet part of the spectrum.
Gallium doped zinc oxide films were deposited in order to investigate the suitability of gallium as a dopant in zinc oxide layers. Highly transparent layers with higher carrier concentrations but lower mobilities compared to aluminium doped zinc oxide were obtained. The dependence of the layer properties on the pressure, doping concentration, substrate temperature and oxygen volume concentration during deposition were studied in order to find the adequate layer to be applied as electrode in thin film solar cells. 4 wt.% Ga2O3 doping concentration was found to be optimal for the production of highly conductive ZnO:Ga layers with a high band gap energy. The incorporation of oxygen gas during the sputter deposition led to more transparent layers at wavelengths longer than 1100 nm, but was found to be detrimental for the electrical properties of the studied layers.
By means of co-sputtering, a set of multi-compound layers formed by Zn-In-Sn-O were deposited and carefully characterised. The resulting layers were studied as a function of the Zn content ratio, which varied between 17.1 to 67.3%. The layers were amorphous in nature but presented embedded nanometric crystals. The incorporation of Zn cations into an indium tin oxide matrix favoured the transmittance but did not modify the mobility. The carrier concentration was found to decrease resulting in an increase in resistivity. The electronic band structure was investigated by means of photoelectron spectroscopy. The measurements showed that, with an increase in Zn concentration, the oxygen vacancy concentration of the surface increased resulting in a degenerately n-doped surface layer. The work function of the material was determined by low intensity X-ray photoelectron spectroscopy and the values varied between 4.7 and 4.3 eV with the variation of Zn content.
The final experiments were focussed on the application of ZnO layers in the back reflectors of pin amorphous silicon solar cells. Trials were performed onto pin structures deposited at T-Solar Global SA and the Universitat de Barcelona.
The cells deposited at T-Solar were long exposed to air before a back reflector could be deposited and evidence for the formation of a thin silicon oxide layer at the interface was obtained. The oxide layer was removed using acid etching in dilute HF, but an analysis by X-ray photoelectron spectroscopy showed that the cleaning step resulted in an important amount of carbon contamination on the surface. Both, the silicon oxide and the carbon layer led to devices with S-shaped J-V curves. Later, the n-type interface was protected by a thin ZnO:Al layer at T-Solar to avoid oxidation during transportation. However, the existence of this thin ZnO:Al protective layer determined the growth of the subsequently deposited layers. Thus, the deposition of ZnO layers under different conditions led to similar results. Finally, different back reflectors were tried over the solar cells fabricated at UB. Aluminium and gallium doped zinc oxide layers were deposited on amorphous silicon pin structures, and a clear improvement in performance with respect to devices with only a metal layer as back reflector was observed. Similar performances were observed when Ga doped ZnO or Al doped ZnO was used in the back reflector. It showed that both gallium and aluminium were suitable dopants for the ZnO to be applied in the back reflector.L'objectiu d'aquest treball rau en l'estudi i optimització dels òxids conductors transparents basats en l'òxid de zinc. Aquests materials, que s'han dipositat mitjançant polvorització catòdica magnetró, es van estudiar amb la finalitat d'emprar-los com elèctrodes en cèl•lules solars de silici en capa prima al Grup d'Energia Solar de la Universitat de Barcelona. En aquesta tesi es presenten les propietats de l'òxid de zinc dopat amb alumini o amb gal•li, així com les propietats de multi-compostos dipositats a partir de la co-polvorització catòdica d'òxid de zinc i d'òxid d'indi dopat amb estany. També es discuteix l'aplicació d'òxids conductors transparents basats en l'òxid de zinc al reflector posterior de cèl•lules solars de silici amorf amb estructura tipus pin. S’ha trobat que l’òxid de zinc dopat amb alumini, a altes temperatures de substrat i altes potències, presenta una elevada transmitància òptica i una baixa resistivitat. La mobilitat de les capes augmentà considerablement fins assolir 68.5 cm2V-1s-1 mitjançant l'aplicació de tractaments tèrmics a alta temperatura previ dipòsit d'una capa protectora de silici amorf o d'alúmina. Pel cas de l'òxid de zinc dopat amb gal•li s'han obtingut una sèrie de capes altament transparents i amb concentracions de portadors superiors, però amb mobilitats inferiors que les de capes dopades amb alumini. Mitjançant co-polvorització d’òxid de zinc i òxid d’indi dopat amb estany s’han obtingut capes amorfes del multi-compost Zn-In-Sn-O amb un contingut de zinc que varia entre el 17.1 i el 67.3%. La incorporació del zinc a l'òxid d'indi dopat amb estany afavoreix l'increment de la transmitància, sense que la mobilitat de les capes es vegi afectada. En canvi, la concentració de portadors disminueix amb la incorporació de Zn. Comparant l'ús del gal•li i de l'alumini com a dopants de l'òxid de zinc del reflector posterior de cèl•lules de silici amorf tipus pin, s'ha observat una gran similitud en el comportament dels dispositius. Això ens ha portat a la conclusió que ambdós materials són adients per ser emprats com a reflectors posteriors.
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Tosoni, Olivier. "Conception, élaboration et intégration d'électrodes transparentes optimisées pour l'extraction des charges dans des dispositifs photovoltaïques." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00955867.
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Les oxydes transparents conducteurs (TCO) ont la rare propriété de concilier haute transparence et conductivité élevée, ce qui en fait des matériaux-clés pour de nombreuses applications requérant des électrodes transparentes comme les cellules photovoltaïques, les diodes organiques et les écrans plats. Avec une résistivité de l'ordre de 10^(-4) ohm.cm et une transmittance de 85% dans le domaine visible, l'oxyde d'indium dopé à l'étain (ITO) est le matériau privilégié. Toutefois, sa fragilité, son instabilité aux procédés plasma et son coût croissant du fait de sa haute teneur en indium sont autant de raisons de rechercher des matériaux alternatifs. Cette thèse a pour but de comprendre les points clefs permettant d'améliorer les performances d'une électrode transparente en oxyde de zinc dopé à l'aluminium (AZO) sur les plans optique, électrique et au niveau des interfaces ; des cellules photovoltaïques en silicium amorphe hydrogéné (a-Si:H) servent de dispositif-test à cette étude. Réalisées par pulvérisation cathodique magnétron sous des conditions de dépôt variées, les couches minces d'AZO obtenues ont une structure microcristalline et, pour des paramètres déterminés, des performances optoélectroniques approchant celles de l'ITO. Un modèle adapté d'après la théorie de Drude a permis de rendre compte du lien entre transparence et conduction et de confirmer la saturation en porteurs du matériau. L'efficacité d'une électrode au sein d'un dispositif dépend également très fortement de l'interface entre celle-ci et l'absorbeur, les porteurs devant être extraits rapidement pour ne pas se recombiner. Quelques voies ont été explorées pour réduire la barrière de potentiel entre le silicium amorphe et l'électrode tout en favorisant l'efficacité optique des cellules. Il ressort que l'insertion d'une couche tampon d'oxyde de titane ou de tungstène permet d'obtenir un gain notable dans les performances des cellules.
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Prabhakar, Tejas. "Study of Earth Abundant TCO and Absorber Materials for Photovoltaic Applications." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1382269621.
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Cruz, Bournazou Alexandros [Verfasser], Bernd [Akademischer Betreuer] Szyszka, Bernd [Akademischer Betreuer] Stannowski, Bernd [Gutachter] Szyszka, Bernd [Gutachter] Stannowski, and Olindo [Gutachter] Isabella. "Transparent conductive oxides for silicon heterojunction solar cells: interaction between materials and device / Alexandros Cruz Bournazou ; Gutachter: Bernd Szyszka, Bernd Stannowski, Olindo Isabella ; Bernd Szyszka, Bernd Stannowski." Berlin : Technische Universität Berlin, 2021. http://d-nb.info/1231908297/34.
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Heinemann, Marc Daniel [Verfasser], Bernd [Akademischer Betreuer] Rech, Michael [Gutachter] Powalla, Bernd [Gutachter] Rech, and Susan [Gutachter] Schorr. "CIGSe superstrate solar cells : growth and characterization of CIGSe thin films on transparent conductive oxides / Marc Daniel Heinemann ; Gutachter: Michael Powalla, Bernd Rech, Susan Schorr ; Betreuer: Bernd Rech." Berlin : Technische Universität Berlin, 2016. http://d-nb.info/115618021X/34.
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Leppänen, K. (Kimmo). "Sample preparation method and synchronized thermography to characterize uniformity of conductive thin films." Doctoral thesis, Oulun yliopisto, 2015. http://urn.fi/urn:isbn:9789526208312.
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Abstract The uniformity of conductive materials is an important property in thin film electronic applications such as solar cells and light emitting diodes (LED). Such uniformity variations are often very small, invisible or below the surface of the film and thus are difficult to detect even when using high-resolution characterization devices. Thus, surface measurement instruments such as profilometer, atomic force microscope, or scanning electron microscope can all encounter remarkable challenges. The uniformity of films can also be analyzed by conductivity measurements. However, they do not provide the precise spatial uniformity information of a large area sample. To be able to investigate systematically the defects of conductive thin films an appropriate sample preparation method was constructed. In addition, a synchronized heating and IR-imaging based system (called synchronized thermography = ST) was developed to overcome the limitations of existing characterization methods. ST performance was tested and analyzed by measuring the single and multi-layer structures. In this work, Indium Tin Oxide (ITO) and poly(3,4-ethylenedioxy-thiopene):poly(styrene-sulfonate) (PEDOT: PSS) were used as examples of conductive thin films. Obtained results show that ST is capable of localizing even small defects from thin film structures based on a single IR-image. In order to make automatic identification of the defect locations and the sizes of the defects, a data processing algorithm was implemented. The performed experiments have proven ST capable of determining the conductivity of the films and the critical bending curvature of ITO. Based on thin film multi-layer PEDOT:PSS measurements, the results suggest use of the ST-method is also suitable for thickness measurements. ST with automatic data processing is a simple method to localize small defects in large-area thin film structures. This approach opens up new possibilities in measuring industrial scale manufacturing processesTiivistelmä Johtavien materiaalien tasalaatuisuus on tärkeä ominaisuus ohutkalvoelektroniikan sovelluksissa kuten aurinkokennoissa ja valoa emittoivissa diodeissa (LED). Tasalaatuisuuserot ovat usein erittäin pieniä, näkymättömiä tai ne sijaitsevat pinnan alla, joten niiden havaitseminen on vaikeaa jopa korkean resoluution karakterisointivälineillä. Niinpä pintaa mittaavat laitteet kuten profilometri, atomivoimamikroskooppi ja skannaava elektronimikroskooppi kohtaavat merkittäviä haasteita. Pinnan tasalaatuisuutta voidaan analysoida myös johtavuusmittauksilla. Ne eivät kuitenkaan anna täsmällistä spatiaalista informaatiota suurista näytteistä. Johtavien ohutkalvojen rikkoutumien systemaattista tutkimista varten kehitettiin oma näytteiden käsittelymenetelmä. Lisäksi kehitettiin synkronoituun lämmitykseen ja infrapunakuvantamiseen perustuva mittaussysteemi (menetelmän nimi: synkronoitu termografia = ST), jolla pyritään ratkaisemaan nykyisten menetelmien rajoitukset. ST-menetelmää testattiin ja analysoitiin mittaamalla yksi- ja monikerroksisten kalvojen rakenteita. Indiumtinaoksidia (ITO) ja poly(3,4-etyleenidioksi-tiofeeni):poly(styreeni-sulfonaatti):a (PEDOT: PSS) käytettiin esimerkkeinä johtavista kalvoista. Tulokset osoittavat, että ST kykenee paikallistamaan pienetkin virheet ohutkalvorakenteista jopa yhden infrapunakuvan perusteella. Automaattisen tiedonkäsittelyn algoritmi implementoitiin identifioimaan virheiden paikkariippuvuuksia ja kokoja. Tehdyt kokeet osoittavat, että ST-menetelmä soveltuu kalvojen johtavuuden ja ITO:n kriittisen taivutussäteen määrittämiseen. Monikerroksisiin PEDOT:PSS rakennemittauksiin perustuen ST-menetelmä näyttäisi soveltuvan myös ohutkalvojen paksuuksien määrittämiseen. ST-menetelmä yhdistettynä automaattiseen mittaustiedon prosessointiin on yksinkertainen menetelmä paikallistamaan pieniä virheitä suuripinta-alaisilla näytteillä. Tämä lähestymistapa avaa uusia mittausmahdollisuuksia teollisuuden tuotantoprosesseihin
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JÃnior, Paulo Herbert FranÃa Maia. "Obtaining a thin film of FTO by spray-pyrolysis technique and sol-gel method for use in organic solar cells." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14347.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoThe growing interest in the use of new materials and their applications for photovoltaic systems has been a constant concern of the scientific community in recent years. This work is primarily engaged in the collection, characterization and photoactivity testing photovoltaic solar cells made of thin SnO2 doped fluoride films, the films were deposited by the technique of "spray-pyrolysis" and the Sol-Gel method in substrate glass. In glasses microscopy work with dimensions of 2.5 x 7.5 x 1 mm are used as matrices for the conductive substrates or transparent conductive oxides (TCO). These glasses have electrical resistance and transmittance adequate for the manufacture of photoelectrochemical solar cells activated by dyes. Besides making the glasses must be made conductive depositing a layer of titanium oxide, preparation of electrolyte, dye, assembly and characterization of the cells. The conductive substrate has a film of tin dioxide doped with fluorine (SnO2: F), the deposition is made with the aid of a compressor and a spray gun on the glass at a temperature of 600Â C from a solution made by the method Sol- gel (MSG). As characterization techniques were used: x-ray diffraction (EDX), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), UV-Vis and Van der Pauw method. The conductive glass has transmittance of 80% (400 nm - 800 nm). The cell with mesoporphyrin dye has Vac = 0.34V and Icc ~ 150μA. The experimental results obtained from these cells may contribute to the development of prototypes that can be used commercially in the capture of solar energy and its consequent transformation into electricity.
O crescente interesse no uso de novos materiais e suas aplicaÃÃes, para sistemas fotovoltaicos tem sido uma constante preocupaÃÃo da comunidade cientifica nos Ãltimos anos. O presente trabalho tem por objetivo principal a obtenÃÃo, caracterizaÃÃo e testes de fotoatividade de cÃlulas solares fotovoltaicas constituÃdas de filmes finos de SnO2 dopados com flÃor, os filmes foram depositados pela tÃcnica de âspray-pirÃliseâ e pelo mÃtodo Sol-Gel em substrato de vidro. Neste trabalho vidros de microscopia com dimensÃo de 2,5 x 7,5 cm x 1 mm, sÃo usados como matrizes para os substratos condutores ou Ãxidos condutores transparentes (OCTâs). Estes vidros possuem resistÃncia elÃtrica e transmitÃncia adequadas para confecÃÃo de cÃlulas solares fotoeletroquÃmicas ativadas por corantes. AlÃm de tornar os vidros condutores deve ser feita a deposiÃÃo de uma camada de Ãxido de titÃnio, preparaÃÃo de eletrÃlito, corante, montagem e caracterizaÃÃo das cÃlulas. O substrato condutor possui um filme de diÃxido de estanho dopado com flÃor (SnO2:F), a deposiÃÃo à feita com o auxilio de um compressor e uma pistola aerogrÃfica sobre o vidro à temperatura de 600ÂC a partir de uma soluÃÃo feita pelo mÃtodo Sol-Gel (MSG). Como tÃcnicas de caracterizaÃÃo foram usadas: difraÃÃo de raios-x (EDX), microscopia eletrÃnica de varredura (MEV), espectroscopia de energia dispersiva (EDS), Uv-Vis e mÃtodo de Van der Pauw. O vidro condutor apresenta transmitÃncia 80% (400 nm â 800 nm ). A cÃlula com corante mesoporfirina apresenta Vca = 0,34 V e Icc ~ 150μA. Os resultados experimentais obtidos dessas cÃlulas poderÃo contribuir para o desenvolvimento de protÃtipos que possam ser utilizados comercialmente na captaÃÃo de energia solar e sua conseqÃente transformaÃÃo em energia elÃtrica.
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Harris, Tomos Gwilym Ab Alun [Verfasser], Anna [Akademischer Betreuer] Fischer, Peter [Akademischer Betreuer] Hildebrandt, Anna [Gutachter] Fischer, Peter [Gutachter] Hildebrandt, and Ulla [Gutachter] Wollenberger. "Surface functionalised and nanostructured transparent conductive oxides : towards a platform for (bio)electrocatalysis / Tomos Gwilym Ab Alun Harris ; Gutachter: Anna Fischer, Peter Hildebrandt, Ulla Wollenberger ; Anna Fischer, Peter Hildebrandt." Berlin : Technische Universität Berlin, 2019. http://d-nb.info/1182423043/34.
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Ramos, Raul 1988. "Estudo das propriedades ópticas e de transporte eletrônico em filmes finos de TiO2 dopados com nitrogênio." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276932.
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Orientador: Luiz Fernando ZagonelDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: Eletrodos condutores transparentes (TCE) possuem grande importância para tecnologias de informação e geração de energia. O TCE mais eficiente na atualidade é o ITO (In2O3 dopado com Sn), que pode alcançar resistividades em torno de 2.10-4 ?cm e uma transmitância ótica de 80% a 90% na região do visível. Entretanto, a escassez dos recursos naturais de Índio e sua grande demanda sugerem a necessidade de materiais alternativos. O presente estudo tem por objetivo investigar as propriedades óticas, eletrônicas e estruturais de filmes finos de TiO2 (fase anatase) dopados com Nitrogênio. A deposição dos filmes foi feita por Deposição por Feixe de Íons (IBD) por bombardeamento de um alvo de titânio puro com íons de Ar+ em atmosfera de O2. Os filmes, com uma espessura de ?90 nm, foram depositados em substrato de quartzo amorfo (Herasil-1) a temperaturas de 400 ou 500°C. Depois, os filmes são dopados com implantação iônica, variando o tempo de 10 a 60 minutos, com feixe de íons misto a baixa energia de N2+ e H2+ com 150 eV e sob a mesma temperatura de crescimento. Após a implantação, medidas Hall indicam que a densidade de portadores majoritários nos filmes de anatase dopados com nitrogênio chegam até ?1019 cm?3 (enquanto filmes não dopados tem densidade de cargas de ?1012 cm?3). A resistividade dos filmes dopados chegam até 10?1 ?cm enquanto mantem boa transmissão ótica (>80%). De fato, dependendo do tempo de dopagem e da temperatura do substrato durante o processo, a transmissão de até 85% podem ser obtida em 550 nm com tal resistividade (?10?1 ?cm). Espectroscopia de fotoelétrons emitidos por raio-x (XPS) realizadas in situ mostram que a composição na superfície é compatível com TiO2?xNx com concentração de nitrogênio de até ? 20%. Difração de raio-x com ângulo de incidência rasante (GIXRD) confirmaram a estrutura cristalina anatase dos filmes antes e após a implantação iônica à baixa energia (150 eV). Este estudo indica que é possível dopar a amostra anatase com nitrogênio através do uso de um feixe de íons de baixa energia. Tal abordagem é interessante por permitir um controle da concentração de dopantes (Nitrogênio através de um precursor gasoso) de forma mais controlada do que usualmente obtido por sputtering reativo
Abstract: Transparent conductive electrodes (TCE) have great importance for information and energy technologies. The most efficient TCE is currently the ITO (Sn-doped In2O3), which may have a resistivity lower than 2·10?4 ?cm and an optical transmittance of 80% to 90% in the visible region. However, the scarcity of natural resources of Indium and its great demand suggests the need of alternative materials. The present study aims to investigate the optical, electronic and structural properties of thin films of TiO2 (anatase phase) doped with nitrogen. The films deposition is made by Ion Beam Deposition (IBD) by bombarding a pure titanium target with Ar+ ions in O2 atmosphere to a thickness of about 90 nm. The films are deposited on an amorphous quartz substrate (Herasil-1) at 400 or 500 °C. Afterwards, the films are doped by ion implantation with low-energy ion beam mixed of N2+ and H2+ at 150 eV and under the same temperature of the growth for times ranging from 10 to 60 minutes. After implantation, Hall measurements indicated that the majority carrier density in the nitrogen doped anatase films reaches up to ? 1019 cm?3 (while the undoped films have a carrier density of ? 1012 cm?3). The resistivity of the doped films is as low as 10?1 ? cm while maintaining good optical transmission. Indeed, depending on the doping time and substrate temperature, transmission of up to 90% could be obtained at 550 nm with this resistivity. X-ray photoelectron spectroscopy (XPS) performed in situ shows that the surface composition is compatible with N:TiO2?x with nitrogen concentrations of up to ? 20%. Small angle x-ray diffraction measurements (SAXRD) confirmed the anatase crystal structure of the films before and after the low energy ion implantation. This study indicates that it is indeed possible to dope anatase thin films with nitrogen by low energy ion beam. This approach is interesting for allowing a greater control of doping concentration with respect to what is usually obtained by reactive sputtering
Mestrado
Física
Mestre em Física
2013/118682-8
CAPES
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Silva, Junior Romualdo Santos. "Propriedades estruturais, elétricas e ópticas do composto LaCrO3 dopado com Al produzido pelo método da combustão." Pós-Graduação em Física, 2018. http://ri.ufs.br/jspui/handle/riufs/9245.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESIn the present work, we performed a study of the structural, electrical and optical properties of the compound LaCr1-xAlxO3 (x = 0.0, 0.05, 0.5, 0.95 and 1.0) produced by the combustion method. The structural analyzes were performed by X-ray diffraction (XRD) and Rietveld refinement, the electrical measurements using impedance spectroscopy and IV measurements, and optical measurements using UV-Vis spectroscopy. The results of XRD allied to the Rietveld method of refinement indicate that the samples with x = 0.0 and 0.05, have an orthorhombic structure belonging to the space group Pnma (62), and for x = 0.5, 0.95 and 1.0, a rhombohedral structure belonging to the space group R-3c (167), thus taking place a structural transition in the material. The impedance spectroscopy measurements associated to the IV curves show that the samples with higher concentration of Al present higher resistance, and the samples with lower concentration of Al present less resistance. We observe that for high frequencies a decrease of dielectric constant with frequency occurs. In addition, the appearance of only a semicircle establishes the presence of non-Debye type relaxation, where an equivalent circuit composed of two resistors (R1 and R2) and a constant phase element (CPE) were used. By means of the absorption measurements in the ultraviolet to visible region (UV-Vis), we estimated the optical gap of the samples, through the tauc equation, which vary between 3.27 - 3.43 eV. Still, we observed that the increase in Al concentration favors the increase in transmittance in the material.
No presente trabalho, realizamos um estudo das propriedades estruturais, elétricas e ópticas do composto LaCr1-xAlxO3 (x=0,0; 0,05; 0,5; 0,95 e 1,0) produzido pelo método da combustão. As análises estruturais foram realizadas por meio de difração de raios-X (DRX) e refinamento Rietveld, as elétricas por meio de espectroscopia de impedância e medidas IV, e ópticas por meio de espectroscopia de UV-Vis. Os resultados de DRX aliados ao método de refinamento Rietveld indicam que as amostras com x = 0,0 e 0,05, apresentam uma estrutura ortorrômbica pertencente ao grupo espacial Pnma (62), e para x = 0,5; 0,95 e 1,0, uma estrutura romboédrica pertencente ao grupo espacial R-3c (167), ocorrendo assim uma transição estrutural no material. As medidas de espectroscopia de impedância associadas às curvas IV mostram que as amostras com maior concentração de Al apresentam maior resistência, e as amostras com menor concentração de Al apresentam menor resistência. Observamos que para altas frequências ocorre uma diminuição da constante dielétrica com a frequência. Além disso, o aparecimento de apenas um semicírculo estabelece a presença do relaxamento do tipo não-Debye, onde foi utilizado um circuito equivalente composto por duas resistências (R1 e R2), e um elemento de fase constante (CPE). Através das medidas de absorção na região do ultravioleta ao visível (UV-Vis) estimamos o gap óptico das amostras, através da equação de tauc, os quais variam entre 3,27 - 3,43 eV. Além disso, observamos que o aumento da concentração de Al favorece o aumento da transmitância no material.
São Cristóvão, SE
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Damiani, Larissa Rodrigues. "Filmes de óxido de índio dopado com estanho depositados por magnetron sputtering." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-31052010-165402/.
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O óxido de índio dopado com estanho é um semicondutor degenerado de alta transparência no espectro visível e alta condutância elétrica. Por suas propriedades, ele é utilizado como eletrodo transparente em diversas aplicações. Algumas destas aplicações exigem que os filmes sejam depositados sobre substratos poliméricos, que degradam em temperaturas acima de 100 °C. Por este motivo, métodos de deposição que utilizam baixas temperaturas são necessários. O objetivo deste trabalho é o desenvolvimento de técnicas de deposição de filmes de óxido de índio dopado com estanho, em baixas temperaturas (< 100 °C), pelo método de magnetron sputtering de rádio fequência. Filmes foram obtidos sobre substratos de silício, vidro e policarbonato, e suas propriedades físicas, elétricas, ópticas, químicas e estruturais foram analisadas por perfilometria, elipsometria, curvas corrente-tensão, prova de quatro pontas, medidas de efeito Hall, difratometria de raios-X e espectrofotometria. Filmes depositados sobre silício e vidro tiveram resistividade elétrica mínima da ordem de 10^-4 Ohm.cm, enquanto a resistividade do filme obtido sobre policarbonato foi da ordem de 10^-3 Ohm.cm. A transmitância óptica média no espectro visível das amostras variou de 66 a 87 %. Do ponto de vista estrutural, as amostras tenderam a apresentar fase amorfa e cristalina, com orientação preferencial ao longo da direção [100]. De modo geral, as amostras obtidas de 75 a 125 W tiveram as melhores propriedades para serem utilizadas em aplicações que exijam eletrodos transparentes, considerando aspectos elétricos e ópticos.Indium-tin oxide is a degenerate semiconductor that shows high transmittance in the visible region of the spectrum and high electrical conductance. Because of its properties, this material is used as transparent electrode in a wide variety of applications. Some of these applications demand the indium-tin oxide layer to be deposited over polymer substrates, which degrade at temperatures above 100 °C. Because of this degradation problem, deposition methods at low temperatures are needed. The purpose of this work is the development of low temperature (< 100 °C) indium-tin oxide deposition processes by radio frequency magnetron sputtering method. Thin films were deposited over silicon, glass and polycarbonate substrates, and their physical, electrical, optical, chemical and structural properties were analyzed by surface high step meter, ellipsometry, current-voltage curves, four-point probe analysis, Hall effect measurements, X-ray diffractometry and spectrophotometry. Films deposited over silicon and glass substrates showed minimal electrical resistivity in the order of 10^-4 Ohm.cm, while the resistivity of the film obtained over polycarbonate was in the order of 10^-3 Ohm.cm. The average transmittance in the visible spectrum varied over the range 66 to 87 %. According to the structural study, the films present both amorphous and crystalline phases, with crystallites showing preferential orientation along the [100] direction. In general, films deposited with power varying over the range 75 to 125 W showed the best results to be applied as transparent electrodes, considering electrical and optical aspects.
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Hill, Theresa Y. "Fabrication of Zinc Oxide Thin Films For Renewable Energy and Sensor Applications." Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1291251851.
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Damiani, Larissa Rodrigues. "Filmes de óxido de zinco e nitreto de zinco depositados por magnetron sputtering com diferentes pressões de argônio, oxigênio e nitrogênio." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-13072016-142431/.
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O óxido de zinco é um material semicondutor que apresenta alta transparência óptica no espectro visível, alta energia de ligação de éxcitons e piezoeletricidade. Por suas propriedades, ele é utilizado na área de sensores, eletrodos transparentes e dispositivos optoeletrônicos. No entanto, sua utilização ainda é limitada pela dificuldade de obtenção de condutividade tipo p, cujo principal dopante é o nitrogênio, devido à assimetria de dopagem ocasionada por defeitos intrínsecos do material, dopagem em valências diferentes das esperadas e formação de níveis de aceitadores profundos na banda proibida. A aplicação em dispositivos piezoelétricos também exige alta resistividade e ótimas propriedades cristalinas. Muitos processos de deposição estabelecidos hoje ainda utilizam altas temperaturas, o que impede sua deposição sobre superfícies ou substratos sensíveis a altas temperaturas. O objetivo deste trabalho é desenvolver técnicas de deposição de filmes de ZnO, principalmente em baixas temperaturas ( 100°C), pelo método de magnetron sputtering de rádio frequência, para avaliar a influência dos gases de processo nas características estruturais, estequiométricas, elétricas e ópticas dos filmes. Para isso, foram obtidos filmes utilizando pressão total de argônio, e pressões parciais de argônio e oxigênio e argônio e nitrogênio, utilizando alvo cerâmico de óxido de zinco ou alvo metálico de zinco. Para alvo de ZnO, filmes com condutividade tipo n foram obtidos em ambiente de argônio, em condições que geraram deficiências de oxigênio. Filmes altamente resistivos foram obtidos com a utilização de pressão parcial de oxigênio no gás de processo, em condições que resultaram em filmes estequiométricos, inclusive com condutividade tipo p. Condutividade tipo p mais alta foi observada, apenas por ponta quente, para uma amostra obtida em argônio logo após a utilização de nitrogênio na câmara de processo, que provavelmente sofreu influência da dopagem não intencional do cobre, que foi identificado como um contaminante do processo devido à estrutura da câmara. Para alvo de Zn, observou-se a formação de nitreto de zinco, que demonstrou alta capacidade de oxidação em ambiente atmosférico, e portanto, transforma-se naturalmente ao longo do tempo ou por processos de oxidação térmica em ZnO dopado com nitrogênio. Filmes de ZnO produzidos a partir de nitreto de zinco foram os únicos dos testados que apresentaram fotoluminescência característica do ZnO, mesmo para processos onde não houve aquecimento intencional.Zinc oxide is a multifunctional semiconductor, which presents high optical transparency in the visible range, high exciton binding energy and piezoelectricity. Due to its properties, ZnO is used in several areas, such as sensors, transparent electrodes and optoelectronics. However, its usage is still limited by the lack of p-type conductivity, which is very difficult to achieve because of intrinsic material defects, unwanted valence states of doping elements and formation of deep acceptor levels. Piezoelectric devices also demand high electrical resistivity and excellent crystallographic properties. Many current deposition processes still apply high temperatures, preventing material deposition onto temperature sensitive substrates and surfaces. The main goal of this investigation is to develop low temperature ( 100°C) deposition techniques by radio frequency magnetron sputtering, to evaluate the influence of process gases in structural, stoichiometric, electrical and optical properties. Thin films were obtained using either pure argon, argon and oxygen or argon and nitrogen partial pressures, by sputtering ceramic ZnO or metallic Zn targets. For ZnO target, n-type conductivity was achieved in argon environment, by creating oxygen deficient films. High resistivity was observed by using oxygen partial pressure, resulting in stoichiometric material and changing carrier type from electrons to holes. Higher p-type conductivity was observed, only by Seebeck measurement, for a nonintentionally heavily doped sample, as there was copper originating from the deposition chamber. For Zn target, zinc nitride formation was observed, showing high capability of transforming itself into nitrogen-doped ZnO by air exposure or thermal annealing. ZnO films produced from zinc nitride were the only ones that exhibited photoluminescence, even when there was no intentional heating involved.
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Soumahoro, Ibrahima. "Elaboration et caractérisation des couches mines de ZnO dopées au molybdène et l'ytterbium, pour des applications photovoltaïques." Thesis, Strasbourg, 2012. http://www.theses.fr/2012STRAE016.
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Dans la perspective d’améliorer les cellules du futur, nous avons élaboré respectivement des couches minces de ZnO dopé Mo par la méthode spray pyrolyse et dopé Yb par sputtering. Quel que soit la technique utilisée, toutes ces couches sont polycristallines, transparentes avec des surfaces uniformes. De plus les mesures d’effet Hall montrent une conductivité de type n dans le cas des deux systèmes étudiés. Concernant les films minces de ZnO dopé Mo, les propriétés électriques restent potentiellement intéressantes pour des applications en photovoltaïque en tant que dopant additionnel en plus des terres rares. Quant aux films minces de ZnOYb, les résultats de mesures PL ont clairement mis en évidence un couplage optique entre ZnO et l’Yb avec l’observation d’un photon infrarouge pour un photon UV incident. Ceci suggère que le concept « down-shift » est susceptible d’être validéIn view of improving the cells of the future, we have elaborated respectively doped ZnO thin films by Mo spray pyrolysis method and doped Yb by sputtering. Whatever the technique used all these layers are polycrystalline, transparent with smooth surfaces. In addition, the Hall effect measurements show an n-type conductivity in the case of two systems studied. On thin films of ZnO doped Mo, the electrical properties are potentially interesting for photovoltaic applications as additional dopant in addition to rare earths. As for thin films ZnOYb, PL measurement results have clearly demonstrated an optical coupling between ZnO and Yb with the observation of a photon infrared photon UV incident. This suggests that the concept of "down-shift" is likely to be validated
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Bikowski, Andre. "The relation between the deposition process and the structural, electronic, and transport properties of magnetron sputtered doped ZnO and Zn1-xMgxO films." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://dx.doi.org/10.18452/16994.
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In dieser Dissertation wurde die Beziehung zwischen den strukturellen, optischen und Ladungstransporteigenschaften von dotierten ZnO- und Zn1-xMgxO-Schichten eingehend untersucht. Das Ziel war es, die oben genannten Zusammenhänge weiter aufzuklären, wodurch sich anschließend Ansätze für eine zielgerichtete Verbesserung der Schichteigenschaften ableiten lassen. Zunächst konzentriert sich die Arbeit auf das Wachstum der ZnO-Schichten, um wichtige strukturelle Parameter, wie zum Beispiel Korngrößen und Defektdichten, mittels Röntgendiffraktometrie und Transmissionselektronenmikroskopie zu bestimmen. Diese strukturellen Parameter wurden dann als Modellparameter für die theoretische Modellierung des Transports der freien Ladungsträger verwendet. Temperaturabhängige Hall-, Leitfähigkeits- und Seebeck-Koeffizient-Messungen zeigten, dass der elektrische Transport hauptsächlich durch die Streuung der Ladungsträger an ionisierten Störstellen und Korngrenzen limitiert wird. Im Rahmen dieser Arbeit wurde die theoretische Beschreibung der Streuung an Korngrenzen auf entartet dotierte Halbleiter erweitert. Diese Ergebnisse wurden dann genutzt, um ein qualitatives Modell zu formulieren, welches den Zusammenhang zwischen dem Magnetron-Sputter-Abscheidungsprozess und den strukturellen und elektrischen Eigenschaften der Schichten herstellt. Gemäß diesem Modell sind die Schichteigenschaften bei niedrigen Abscheidungstemperaturen hauptsächlich durch die Bildung akzeptoratiger Sauerstoffzwischengitterdefekte bestimmt, die einen Teil der extrinsischen Dotanden kompensieren. Diese Defekte werden durch ein Bombardement der wachsenden Schicht mit hochenergetischen negativen Sauerstoffionen verursacht. Bei höheren Abscheidungstemperaturen dominiert die Bildung von sekundären Phasen oder Defektkomplexen, in denen der Dotant elektrisch inaktiv ist.In this thesis, the relation between the structural, optical, and charge carrier transport properties of magnetron sputtered doped ZnO and Zn1-xMgxO films has been investigated in detail. The objective was to clarify the above mentioned relations, which allows to derive solutions for a deliberate improvement of the layer properties. The work first focusses on the growth of the ZnO layers to determine important structural properties like grain sizes and defect densities via X-ray diffraction and transmission electron microscopy investigations. These structural properties were then used as model parameters for the theoretical modelling of the charge carrier transport. The temperature dependent Hall, conductivity and Seebeck coefficient measurements show that the transport is mainly limited by grain boundary scattering and ionized impurity scattering. The theoretical description of the grain boundary scattering has been extended in this work to also include degenerate semiconductors. Based on the results on the structural and electronic properties, in a next step a qualitative model was developed which explains the correlation between the magnetron sputtering deposition process and the structural and electronic properties of the films. According to this model, the properties of the films are mainly influenced by the formation of electrically active acceptor-like oxygen interstitial defects at low deposition temperatures, which lead to a partial compensation of the extrinsic donors. These defects are caused by a bombardment of the growing film by high-energetic negative oxygen ions. At higher deposition temperatures, the formation of secondary phases or defect complexes, in which the dopant is electrically inactive, prevails.
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Nazarzadehmoafi, Maryam. "Electronic properties of metal-In 2 O 3 interfaces." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2017. http://dx.doi.org/10.18452/17771.
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Das Verhalten der elektronischen Eigenschaften von gespaltenen, aus der Schmelze gezüchteten In2O3-(111) Kristallen wurde bei Deposition von Edelmetallen, In und Sn mittels winkelaufgelöster Photoelektronen-Spektroskopie untersucht. Die Stöchiometrie, strukturelle Qualität und Kristall-Orientierung, die Oberflächenmorphologie und die Elektronenkonzentration wurden jeweils mittels energiedispersiver Röntgenspektroskopie, Laue-Beugung, Raster Tunnel-Mikroskopie (STM) und Hall-Effekt untersucht. Die Ähnlichkeit der fundamentalen und Oberflächen-Bandlücken kann auf das fast flache Verhalten der Bänder auf der gespaltenen Oberfläche der Kristalle zurückgeführt werden. Die Grenzflächen von Ag und Au/In2O3 zeigen Schottky-Verhalten, während ein ohmscher in Cu, In und Sn /In2O3-Kontakten beobachtet wurde. Aufgrund der Übereinstimmung zwischen optischen und Oberflächen-Bandlücken, der Bildung eines Gleichrichterkontaktes und des Auftretens der Oberflächenphotospannung auf der frischen Kristalloberfläche kann gefolgert werden, dass SEAL nicht eine intrinsische Eigenschaft der gespaltenen Oberfläche der untersuchten Kristalle ist. Des Weiteren wurden bei dicker Au- und Cu-Beschichtung von In2O3 bei Raumtemperatur Shockley-artige Oberflächenzustände beobachtet. Zusätzlich wurde die erste Phase des Wachstums von Cu und In auf In2O3 von der Ausbildung eines 2-dimensionalen Elektrongases (2DEG) begleitet, welches bei dickeren Schichten verschwand, die von dem auf reinen Oberflächen von dünnen In2O3- Filmen gemessenen 2DEG verschieden sind. Nach Messung der Austrittarbeit von In2O3 und den jeweils untersuchten Metallen in situ und unter Verwendung der Schottky-Mott-Regel trat außer bei Ag/In2O3 eine deutliche Abweichung auf. Die experimentellen Ergebnisse stimmen auch mit fortgeschrittenen Theorien, die auf dem Elektronegativitätskonzept und MIGS–Modellen basieren, nicht überein.The behavior of the electronic properties of as-cleaved melt-grown In2O3 (111) single crystals was studied upon noble metals, In and Sn deposition using angle-resolved photoemission spectroscopy. The stoichiometry, structural quality and crystal orientation, surface morphology, and the electron concentration were examined by energy dispersive X-ray spectroscopy, Laue diffraction, scanning tunneling microscopy (STM), and Hall-effect measurement, respectively. The similarity of the measured-fundamental and surface-band gaps reveals the nearly flat behavior of the bands at the as-cleaved surface of the crystals. Ag and Au/In2O3 interfaces show Schottky behavior, while an ohmic one was observed in Cu, In, and Sn/In2O3 contacts. From agreement of the bulk and surface band gaps, rectifying contact formation as well as the occurrence of photovoltage effect at the pristine surface of the crystals, it can be deduced that SEAL is not an intrinsic property of the as-cleaved surface of the studied crystals. Moreover, for thick Au and Cu overlayer regime at room temperature, Shockley-like surface states were observed. Additionally, the initial stage of Cu and In growth on In2O3 was accompanied by the formation of a two dimensional electron gas (2DEG) fading away for higher coverages which are not associated with the earlier-detected 2DEG at the surface of In2O3 thin films. The application of the Schottky-Mott rule, using in situ-measured work functions of In2O3 and the metals, showed a strong disagreement for all the interfaces except for Ag/In2O3. The experimental data also disagree with more advanced theories based on the electronegativity concept and metal-induced gap states models.
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Trenque, Isabelle. "Synthèse et caractérisation d’oxydes métalliques ZnO au bénéfice de nouvelles stratégies d’élaboration d’absorbeurs IR." Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR14905/document.
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L’oxyde de zinc dopé de type n est un excellent candidat pour la réalisation de films transparents et isolants thermiques grâce à ses propriétés d’absorption et de réflexion limitées aux domaines UV et IR. La synthèse en milieu polyol de particules nanostructurées d’oxyde de zinc dopé par du gallium a été utilisée afin de maîtriser la morphologie des cristallites. Il a été démontré expérimentalement et théoriquement que le maximum d’efficacité d’absorption IR est atteint pour un taux de dopant de 2,6 % molaire. Des suspensions de haute transmission dans le visible et absorption infrarouge significative ont été obtenues par l’encapsulation des particules avec un matériau fluoré d’indice de réfraction intermédiaire entre l’oxyde et le milieu dispersant, ainsi que par l’optimisation de l’état de dispersion de suspensions colloïdales grâce à l’adsorption de thioalcanes en surface des cristallites de ZnO dopésThanks to its absorption / reflexion properties limited to the UV and the IR range, n-doped zinc oxide is a promising candidate for the elaboration of transparent and insulating films in smart windows. Nanostructured particles of Ga-doped zinc oxide were elaborated by polyol process. Polyol process was used in order to control the size and the morphology of the particles. Both experimental and theoretical data show that a maximum of IR absorption efficiency is obtained for a doping rate of 2.6 molar percent. Colloidal suspensions with high transmission in the visible range combined with significant absorption of the near infrared range were obtained using two strategies. The first one is the encapsulation of the Ga-doped ZnO particles by a fluoride shells with an intermediate refractive index between ZnO and the dispersion medium. The second one is the optimization of the dispersion state of nano-colloidal suspensions thanks to the adsorption of thioalkanes on the Ga-doped ZnO crystallite surfaces
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"Investigation of the Evolution of Conduction Mechanism in Metal on Transparent Conductive Oxides Thin Film System." Master's thesis, 2012. http://hdl.handle.net/2286/R.I.14949.
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abstract: This thesis discusses the evolution of conduction mechanism in the silver (Ag) on zinc oxide (ZnO) thin film system with respect to the Ag morphology. As a plausible substitute for indium tin oxide (ITO), TCO/Metal/TCO (TMT) structure has received a lot of attentions as a prospective ITO substitute due to its low resistivity and desirable transmittance. However, the detailed conduction mechanism is not fully understood. In an attempt to investigate the conduction mechanism of the ZnO/Ag/ZnO thin film system with respect to the Ag microstructure, the top ZnO layer is removed, which offers a better view of Ag morphology by using scanning electron microscopy (SEM). With 2 nm thick Ag layer, it is seen that the Ag forms discrete islands with small islands size (r), but large separation (s); also the effective resistivity of the system is extremely high. This regime is designated as dielectric zone. In this regime, thermionic emission and activated tunneling conduction mechanisms are considered. Based on simulations, when "s" was beyond 6 nm, thermionic emission dominates; with "s" less than 6 nm, activated tunneling is the dominating mechanism. As the Ag thickness increases, the individual islands coalesce and Ag clusters are formed. At certain Ag thickness, there are one or several Ag clusters that percolate the ZnO film, and the effective resistivity of the system exhibits a tremendous drop simultaneously, because the conducting electrons do not need to overcome huge ZnO barrier to transport. This is recognized as percolation zone. As the Ag thickness grows, Ag film becomes more continuous and there are no individual islands left on the surface. The effective resistivity decreases and is comparable to the characteristics of metallic materials, so this regime is categorized as metallic zone. The simulation of the Ag thin film resistivity is performed in terms of Ag thickness, and the experimental data fits the simulation well, which supports the proposed models. Hall measurement and four point probe measurement are carried out to characterize the electrical properties of the thin film system.Dissertation/Thesis
M.S. Materials Science and Engineering 2012
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Tsai, Yun-Zhang, and 蔡昀璋. "Fabricating high transmission TCO/Ag/TCO multilayer films for transparent conductive films application." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/8ebfj3.
Full textAbstract:
碩士國立中山大學
材料與光電科學學系研究所
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In nowadays, transparent conductive thin films (TCFs) are applied in many electronic devices of technologies such as flat panel display, electrode, and so on. It provides convenient life to us. The indium tin oxide is the most popular material in TCFs. However, with shortage of indium in Earth’s crust, high cost due to market demand, and toxic substance for environment. Thus, we should find alternative material to replace it. The research of transparent conductive films applying for electrode, we used ZnO/Cu/Ag/ZnO multilayer films structure (sandwich structure of O/M/O). We designed this structure for two purposes. First, electrical conductivity in metals are higher than ITO. Thus, we expected that Ag thin having well conductivity on thinner thickness films without sacrificing much of transmittance. Second, use thin Ag layer embedded in ZnO layers for the multilayer structure. The thickness of each layer is designed to minimize the reflectance by destructive interference between two layers. Thus, it can increase transmittance in visible range. However, ultrathin silver layer has poor wetting properties on the substrate. It is generally formed island structure when the silver layer is less than 8 nm thickness. It results in larger electrical resistance and optical scattering, to degrades the TCFs performance. Therefore, the research mainly discusses two parts. The first part is to use the SEM, n&k analyzer and four-point probe to observe the results under the control of deposition rate and copper seed layer, the silver thin layer forms smooth surface to improve conductivity on thinner thickness (less than 10 nm). The second part, using a sandwich structure to reduce the reflectance, the transmittance in the visible range can be effectively improved. Consequently, the performance (Haack’s figure of merit) can be improved by suitable adjusting the sandwich structure. For the ZnO/Cu/Ag/ZnO structure with (20/1/8/30 nm) in thickness, the figure of merit was determined to be 16817 (x10-6 Ω-1), which is higher than the figure of merit for the commercial ITO (185-nm), 15526 (x10-6 Ω-1). The sandwich layer structure, with much lower thickness, is stable under ambient condition, and better performance than the commercial ITO glasses.
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Murdoch, Graham. "Transparent Conductive Oxides for Organic Photovoltaics." Thesis, 2010. http://hdl.handle.net/1807/24268.
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Organic solar cells and organic light emitting diodes are on the forefront of
emerging technologies aimed at harnessing light in ways never thought possible. Largear installations of OLED solid state lighting (SSL), as well as organic photovoltaics(OPVs), will become possible as the efficiencies of these devices continue to rise. All organic solar cells and OLEDs require the use of transparent conductive electrodes.Indium oxide (ITO) is currently the transparent conductor of choice for these
applications, due to its unique combination of transparency, high conductivity, durability,and favourable surface properties.
Indium, however, is a rare and expensive metal; proposed large-area installations
of OPV cells and OLEDs will add further strain to global indium supply. Transparent
conductive materials that are abundant, inexpensive, and which enable efficient and
robust organic devices must therefore be developed. In the present work, suitable ITO
anode replacement materials are demonstrated for OLEDS, small-molecule, polymer, and
PbS colloidal quantum dot photovoltaics.