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1
Min, Yongki 1965. "Properties and sensor performance of zinc oxide thin films." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/17032.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2003.Includes bibliographical references (p. 144-152).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Reactively sputtered ZnO thin film gas sensors were fabricated onto Si wafers. The atmosphere dependent electrical response of the ZnO micro arrays was examined. The effects of processing conditions on the properties and sensor performance of ZnO films were investigated. Using AFM, SEM, XRD and WDS, the 02/Ar ratios during sputtering and Al dopant were found to control the property of ZnO films. Subsequent annealing at 700 C improved the sensor response of the films considerably although it had only minor effects on the microstructure. DC resistance, I-V curves and AC impedance were utilized to investigate the gas response of ZnO sensors. ZnO films prepared with high O2/Ar ratios showed better sensitivity to various gases, a feature believed to be related to their lower carrier density. Al doped ZnO showed measurable sensitivity even with lower resistance attributable to their porous microstructure. AC impedance identified two major components of the total resistance including Schottky barriers at the Pt-ZnO interfaces and a DC bias induced constriction resistance within the ZnO films. Time dependent drift in resistance of ZnO films has been observed. Without applied bias, the ZnO films showed a fast and a slow resistance change response when exposed to gases with varying oxygen partial pressure with both response components dependent on operating temperature. Even at the relatively low operating temperatures of these thin film sensors, bulk diffusion cannot be discounted. The oxygen partial pressure dependence of the sensor resistance and its corresponding activation energy were related to defect process controlling the reduction/oxidation behavior of the ZnO.
(cont.) In this study, time dependent DC bias effects on resistance drift were first discovered and characterized. The DC bias creates particularly high electric fields in these micro devices given that the spacing of the interdigited electrodes falls in the range of microns. The high electric field is believed to initiate ion migration and/or modulate grain boundary barrier heights, inducing resistance drift with time. Such DC bias resistance induced drift is expected to contribute to the instability of thin film micro array sensors designed for practical applications. Suggestions for stabilizing sensor response are provided.
by Yongki Min.
Ph.D.
2
Li, Sonny X. "Nitrogen doped zinc oxide thin film." Berkeley, Calif. : Oak Ridge, Tenn. : Lawrence Berkeley National Laboratory ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2003. http://www.osti.gov/servlets/purl/821916-VLVAK9/native/.
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Thesis (M.S.); Submitted to the University of California, Berkeley, 210 Hearst Mining Memorial Bldg., Berkeley, CA 94720 (US); 15 Dec 2003.Published through the Information Bridge: DOE Scientific and Technical Information. "LBNL--54116" Li, Sonny X. USDOE Director. Office of Science. Basic Energy Sciences (US) 12/15/2003. Report is also available in paper and microfiche from NTIS.
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Mahmood, Farkhund Shakeel. "Electrical and optical properties of RF sputtered ZnO thin films." Thesis, Keele University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297202.
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Lee, Jim 1963. "Microstructure and properties of zinc oxide nano-crystalline thin films and composites." Thesis, University of Auckland, 2006. http://hdl.handle.net/2292/2136.
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Zinc oxide (ZnO) is a II–VI compound semiconductor with a wide direct band-gap of 3.3 eV and a hexagonal structure. ZnO is often used in the paint, paper, rubber, food and drug industries. It is also a promising material in nanotechnology applications, for example in nano-electronics and nano-robotic technology. With its wide band-gap, high exciton binding energy and high breakdown strength, ZnO can be utilized for electronic and photonic devices, as well as for high-frequency applications. To produce such optoelectronic devices, control of electronic properties, such as the nature of conduction and carrier density, is required. However, such control has proved difficult for ZnO. Much research has been done to pursue p type ZnO using different processing techniques, however, there are few reports addressing the relationships of microstructure on optical and electrical properties, ion implantation doping of ZnO and nano-ZnO polymer composites. The objectives of this project are to study the processing, composition, microstructure, electronic, optical, UV and electromagnetic shielding properties of ZnO thin films and composites; to explore ion implantation as a method to dope Al, Ag, Sb, Sn and TiN into ZnO thin films or single crystals; to develop conducting, transparent oxide films and/or p-type semiconductor for potential device applications; and to study the relationships of doping, microstructure and electro-optical properties of ZnO thin films and nano-ZnO polymer composites. The experimental work included annealing, characterizing and implantation of magnetron sputtering ZnO thins films and ZnO single crystals. Ion implantation was employed to dope ZnO thin films or single crystals with Ti, N, Sb, Al, Sn and Ag. The diffusion behaviour of implanted and annealed ZnO and the ellipsometry of implanted ZnO thin films were investigated. The relationship of microstructure and properties of as-deposited, annealed and implanted ZnO was studied. The results show that compared to direct current (d.c.) sputtering, the films produced using radio frequency (r.f.) have significantly lower resistivity, porosity and stress. The residual stress can change the band gap of ZnO thin films. Conductivity experiments suggest that the conduction mechanism of sputtered ZnO thin films involves charge transport in the conduction band and electronic hopping between the nearest neighbour donor levels. Furthermore, the optical transmission of ZnO thin films is high in the visible, with excellent UV absorption properties. It is also found that annealing alters the grain size and composition, and reduces the stress of ZnO thin films. Moreover, ion implantation causes partial amorphousness of ZnO films in the implantation zone and introduces stress and interstitial dopants. Transport of Ions in Matter (TRIM) modelling and Secondary Ion Mass Spectrometer (SIMS) analysis confirm that lighter elements implant deeper than heavy elements. The implanted ZnO shows some p type tendency and evidence of photoluminescence. Lastly, the nano-ZnO and polymer composites show excellent mechanical, good UV barrier properties.
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Zhang, Hong Bo. "Optical and electrical properties of ZnO thin films prepared by pulsed laser deposition." HKBU Institutional Repository, 2000. http://repository.hkbu.edu.hk/etd_ra/225.
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Бересток, Таїсія Олександрівна, Таисия Александровна Бересток, Taisiia Oleksandrivna Berestok, Денис Ігорович Курбатов, Денис Игоревич Курбатов, Denys Ihorovych Kurbatov, Надія Миколаївна Опанасюк, et al. "Structural Properties of ZnO Thin Films Obtained by Chemical Bath Deposition Technique." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35076.
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Zinc oxide thin films have been deposited onto glass substrate from zinc sulfate, ammonia and thiourea
aqueous solution by chemical bath deposition. In the work this were specified solution preparation procedure
and optimized the composition of the solution and content of component in it. X-ray difraction and
high-resolution scanning electron microscopy were used to characterize structure formation of obtaining
ZnO films. As a result of investigation was determined the effect of time deposition on the structural and
substructural properties such as lattice parameters, texture quality, coherent scattering domain size.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35076
7
Xie, Xing. "Optical properties of ZnO thin film : raman spectroscopy, optical reflection, photoluminescence and stimulated emission /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202005%20XIE.
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Chan, Ray Yu Wai. "Optical and electrical properties of aluminum-doped ZnO." HKBU Institutional Repository, 2015. https://repository.hkbu.edu.hk/etd_oa/174.
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In the past few years, “green technologies and touch screen technologies for portable devices has came to hot topic in consumer market. The demand for transparent conducting oxides (TCO) is increasing continuously. Therefore, the potential replacement of indium tin oxide (ITO), which is the most widely used TCO in industry, by aluminum zinc oxide (AZO) draws much attention in order to solve the problem of shortage of ITO one day due to the consisting of rare-earth element. In this work, electrical and optical properties of AZO had been characterized according to different sputtering parameters such as oxygen contents, working pressures and gas flow ratios. Physics of electrical conduction and optical transparency of AZO films were revealed and analyzed in order to set up a more complete relationship between mechanism and performance. Meanwhile, a comparison of sensitivity between AZO and zinc oxide (ZnO) to sputtering environment had been made and behaviors of AZO at low temperature had been presented. Optimum sputtering conditions for AZO had been established as a function of sputtering time and the film resistivity reached down to 7 x 10-4 Ω·cm while film transmittance was above 85% when t = 140 mins having film thickness about 610 nm. Degradation of AZO had been investigated. Application of AZO in OLED fabrication had been carried out after film refinement and device performance had been given. Finally, simulation of OLED structure was done for better device performance
9
Matsumura, Masashi. "Synthesis, electrical properties, and optical characterization of hybrid zinc oxide/polymer thin films and nanostructures." Birmingham, Ala. : University of Alabama at Birmingham, 2007. https://www.mhsl.uab.edu/dt/2009r/matsumura.pdf.
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Thesis (Ph. D.)--University of Alabama at Birmingham, 2007.Title from PDF t.p. (viewed Feb. 3, 2010). Additional advisors: Derrick R. Dean, Sergey B. Mirov, Sergey Vyazovkin, Mary Ellen Zvanut. Includes bibliographical references (p. 122-145).
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Silva, Erica Pereira da [UNESP]. "Síntese e caracterização de filmes finos de óxido de zinco." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/99688.
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silva_ep_me_bauru.pdf: 1073739 bytes, checksum: 6cb2c38a70de68a1096aadef2cb3a584 (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Neste trabalho filmes finos de ZnO foram depositados em substratos de vidro pela técnica de RF magnetron sputtering. Como precursores foram utilizados um alvo de zinco metálico e gás oxigênio. Duas séries de filmes finos de ZnO foram obtidas. Na primeira, foram obtidos filmes de ZnO eletricamente isolantes com transmitância óptica acima de 80%. Na segunda série de deposição, os filmes finos de ZnO também apresentaram transmitância óptica na região do visível em torno de 80%. Porém, nesta série os filmes apresentaram baixos valores de resistividade elétrica, em torno de 1,6 x 10-3Ώ cm. Os resultados de morfologia superficial das duas séries, mostraram que as estruturas de grãos dos filmes finos de ZnO evoluíram em tamanho e altura com o aumento da espessura. As análises de difração de raios X realizadas para os filmes de ZnO mostraam um pico preferencial no plano (002), correspondente a estrutura wurtzita do ZnO, classificando os filmes como policristalinos
In this work ZnO films were deposited on glass substrates by RF magnetron sputtering technique. A target of metallic zinc and oxygen gas were used as precursors. Two series of ZnO thin films were obtained. in the first ZnO films were obtained with high optical transmittance, above 80%, but the films showed a high electrical resistivity. In the second set of depositions, the ZnO thin films also showed a high optical transmittance in the visible region, around 80%. However, this samples had low resistivity values, about 1.6x10-3Ώ cm. The results of the surface morphology of the two series showed that the grain structures of ZnO thin films developed in size and heigh with increasing thickness. The analysis of X-ray diffraction for the ZnO films showed a peak in the preferred plan (002), corresponding to the ZnO wurtzite structure, classifying films as polycrystalline
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Курбатов, Денис Ігорович, Денис Игоревич Курбатов, Denys Ihorovych Kurbatov, Олексій Володимирович Климов, Алексей Владимирович Климов, Oleksii Volodymyrovych Klymov, and D. O. Ladnyi. "Characterizations of Structural Properties of ZnO Thin Films Depending on the Experimental Conditions." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/40814.
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Zinc oxide (ZnO) is one of the most promising materials for the fabrication of optoelectronic devices operating in the blue and ultra-violet (UV) spectral regions, owing to its direct wide band gap (Eg ~3.37 eV) and
large exciton binding energy (~60 meV).
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Silva, Érica Pereira da. "Síntese e caracterização de filmes finos de óxido de zinco /." Sorocaba, 2012. http://hdl.handle.net/11449/99688.
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Orientador: José Roberto Ribeiro BortoletoBanca: Monica Alonso Cotta
Banca: Tersio Guilherme de Souza Cruz
O Programa de Pós Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi
Resumo: Neste trabalho filmes finos de ZnO foram depositados em substratos de vidro pela técnica de RF magnetron sputtering. Como precursores foram utilizados um alvo de zinco metálico e gás oxigênio. Duas séries de filmes finos de ZnO foram obtidas. Na primeira, foram obtidos filmes de ZnO eletricamente isolantes com transmitância óptica acima de 80%. Na segunda série de deposição, os filmes finos de ZnO também apresentaram transmitância óptica na região do visível em torno de 80%. Porém, nesta série os filmes apresentaram baixos valores de resistividade elétrica, em torno de 1,6 x 10-3Ώ cm. Os resultados de morfologia superficial das duas séries, mostraram que as estruturas de grãos dos filmes finos de ZnO evoluíram em tamanho e altura com o aumento da espessura. As análises de difração de raios X realizadas para os filmes de ZnO mostraam um pico preferencial no plano (002), correspondente a estrutura wurtzita do ZnO, classificando os filmes como policristalinos
Abstract: In this work ZnO films were deposited on glass substrates by RF magnetron sputtering technique. A target of metallic zinc and oxygen gas were used as precursors. Two series of ZnO thin films were obtained. in the first ZnO films were obtained with high optical transmittance, above 80%, but the films showed a high electrical resistivity. In the second set of depositions, the ZnO thin films also showed a high optical transmittance in the visible region, around 80%. However, this samples had low resistivity values, about 1.6x10-3Ώ cm. The results of the surface morphology of the two series showed that the grain structures of ZnO thin films developed in size and heigh with increasing thickness. The analysis of X-ray diffraction for the ZnO films showed a peak in the preferred plan (002), corresponding to the ZnO wurtzite structure, classifying films as polycrystalline
Mestre
13
Beal, Russell Joseph. "Effects of Nanoassembly on the Optoelectronic Properties of CdTe - ZnO Nanocomposite Thin Films for Use in Photovoltaic Devices." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/283601.
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Quantum-scale semiconductors embedded in an electrically-active matrix have the potential to improve photovoltaic (PV) device power conversion efficiencies by allowing the solar spectral absorption and photocarrier transport properties to be tuned through the control of short and long range structure. In the present work, the effects of phase assembly on quantum confinement effects and carrier transport were investigated in CdTe - ZnO nanocomposite thin films for use as a spectrally sensitized n-type heterojunction element. The nanocomposites were deposited via a dual-source, sequential radio-frequency (RF) sputter technique that offers the unique opportunity for in-situ control of the CdTe phase spatial distribution within the ZnO matrix. The manipulation of the spatial distribution of the CdTe nanophase allowed for variation in the electromagnetic coupling interactions between semiconductor domains and accompanying changes in the effective carrier confinement volume and associated spectral absorption properties. Deposition conditions favoring CdTe connectivity had a red shift in absorption energy onset in comparison to phase assemblies with a more isolated CdTe phase. While manipulating the absorption properties is of significant interest, the electronic behavior of the nanocomposite must also be considered. The continuity of both the matrix and the CdTe influenced the mobility pathways for carriers generated within their respective phases. Photoconductivity of the nanocomposite, dependent upon the combined influences of nanostructure-mediated optical absorption and carrier transport path, increased with an increased semiconductor nanoparticle number density along the applied field direction. Mobility of the carriers in the nanocomposite was further mediated by the interface between the ZnO and CdTe nanophases which acts as a source of carrier scattering centers. These effects were influenced by low temperature annealing of the nanocomposite which served to increase the crystallinity of the phases without modification of the as-deposited phase assembly and associated absorption properties. Integration of the nanocomposite as an n-type heterojunction element into a PV device demonstrated the ability to tune device response based on the spectral absorption of the nanocomposite sensitizer film as dictated by the phase assembly. Overall the various phase assemblies studied provided increased opportunity for optimization of the absorption and carrier transport properties of the nanocomposite thin films.
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Maller, Robert. "Defects and dopants in zinc oxide : a study of the optoelectronic properties of thin films prepared by spray pyrolysis." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/43373.
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Interest in transparent conducting oxides (TCOs) has intensified over the past decade, driven by the requirement to find a suitable replacement to indium tin oxide (ITO). Of the many possible candidates identified, zinc oxide (ZnO) was selected owing to its favourable optical properties, abundance, low toxicity and chemical stability. This thesis is directed towards finding low cost routes to producing transparent conducting ZnO thin films that could be utilised in a range of current and emerging optoelectronic devices. The spray pyrolysis technique is demonstrated as a highly appropriate low cost, large area deposition route to produce ZnO thin films. The necessity for, and the construction of, an automated rig for the deposition process is detailed. Excellent reproducibility is demonstrated compared with manual deposition. The structural, electrical and optical properties of native and doped ZnO are examined with the overall aim to optimise performance for TCO applications. The novel, AC Hall effect technique is employed to study the factors controlling charge carrier concentration and charge mobility across the a wide doping range, including in previously unexplored regions such as in the undoped and low doping regimes. Investigations into the optimal crystal structure for the greatest charge carrier concentration and charge mobility are made and links between the degree of (002) texturing and charge mobility suggested. Further studies into the position of Al, Ga and In dopants in the crystalline lattice show that the ionic radius plays a key role in the solubility of the dopant in the lattice. Ingress and egress of the zinc vacancy (VZn), and emergence of the hybrid dopant substitution/zinc vacancy (XZnVZn where X = Al, Ga, In) defects are suggested as likely candidate to explain observed electronic behaviour. Finally, the effect of annealing ZnO films is studied, and the necessity for Zn-rich films for TCO applications determined. Annealing in oxygen poor environments is shown to greatly reduce resistivity of films, with VZn defects suggested to be the main contributor to this effect. The stability of electronic improvements following annealing is presented; no observable degradation in performance is seen subsequent to 180 days storage in ambient conditions.
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Ortel, Marlis [Verfasser]. "Film growth and electrical properties of solution processed zinc oxide in thin film transistors / Marlis Ortel." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2013. http://d-nb.info/1037012801/34.
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Lamb, D. A. "A study into the growth kinetics and properties of thin film zinc oxide deposited by MOCVD." Thesis, Bangor University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429855.
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Kernan, Forest Emerson. "Material Characterization of Zinc Oxide in Bulk and Nanowire Form at Terahertz Frequencies." PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/510.
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Many new applications are being proposed and developed for use in the terahertz (THz) frequency region. Similarly, many new materials are being characterized for possible use in this area. Nanostructured forms are of particular interest since they may yield desirable properties, but they remain especially challenging to characterize. This work focuses on the characterization of zinc oxide (ZnO) in bulk and nanowire form. A method for characterizing nanostructures at THz by use of a parallel-plate waveguide (PPWG) is presented. This method is novel in that it is simple, both in theory and practice, and does not require the use of complex measurement techniques such as differential and double modulated terahertz time-domain spectroscopy (THz-TDS). To enable easy evaluation of the quality of the result the maximum deviation in the material response measurement is presented. The dielectric properties of bulk and nanowire ZnO as determined by THz-TDS measurements are reported, and the electrical conductivity extracted from both are presented for comparison. Experimental results are compared to the well established pseudo-harmonic phonon dielectric model. Shortcomings in the pseudo-harmonic phonon model are resolved when coupled with a modified Drude model. This work will enable the determination of THz material properties from nano-scale and very-thin film materials with better reliability and practicality than what has been possible until now.
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Kuo, Fang-Ling. "Electrical and Structure Properties of High-κ Barium Tantalite and Aluminum Oxide Interface with Zinc Oxide for Applications in Transparent Thin Film Transistors." Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc84233/.
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ZnO has generated interest for flexible electronics/optoelectronic applications including transparent thin film transistors (TFTs). For this application, low temperature processes that simultaneously yield good electrical conductivity and optical transparency and that are compatible with flexible substrates such as plastic, are of paramount significance. Further, gate oxides are a critical component of TFTs, and must exhibit low leakage currents and self-healing breakdown in order to ensure optimal TFTs switching performance and reliability. Thus, the objective of this work was twofold: (1) develop an understanding of the processing-structure-property relationships of ZnO and high-κ BaTa2O6 and Al2O3 (2) understand the electronic defect structure of BaTa2O6 /ZnO and Al2O3/ZnO interfaces and develop insight to how such interfaces may impact the switching characteristics (speed and switching power) of TFTs featuring these materials. Of the ZnO films grown by atomic layer deposition (ALD), pulsed laser deposition (PLD) and magnetron sputtering at 100-200 °C, the latter method exhibited the best combination of n-type electrical conductivity and optical transparency. These determinations were made using a combination of photoluminescence, photoluminescence excitation, absorption edge and Hall measurements. Metal-insulator-semiconductor devices were then fabricated with sputtered ZnO and high-κ BaTa2O6 and Al2O3 and the interfaces of high-κ BaTa2O6 and Al2O3 with ZnO were analyzed using frequency dependent C-V and G-V measurements. The insulator films were deposited at room temperature by magnetron sputtering using optimized processing conditions. Although the Al2O3 films exhibited a lower breakdown strength and catastrophic breakdown behavior compared to BaTa2O6/ZnO interface, the Al2O3/ZnO interface was characterized by more than an order of magnitude smaller density of interface traps and interface trapped charge. The BaTa2O6 films in addition were characterized by a significantly higher concentration of fixed oxide charge. The transition from accumulation to inversion in the Al2O3 MIS structure was considerably sharper, and occurred at less than one tenth of the voltage required for the same transition in the BaTa2O6 case. The frequency dispersion effects were also noticeably more severe in the BaTa2O6 structures. XPS results suggest that acceptor-like structural defects associated with oxygen vacancies in the non-stoichiometric BaTa2O6 films are responsible for the extensive electrical trapping and poor high frequency response. The Al2O3 films were essentially stoichiometric. The results indicate that amorphous Al2O3 is better suited than BaTa2O6 as a gate oxide for transparent thin film transistor applications where low temperature processing is a prerequisite, assuming of course that the operation voltage of such devices is lower than the breakdown voltage. Also, the operation power for the devices with amorphous Al2O3 is lower than the case for devices with BaTa2O6 due to the smaller fixed oxide charges and interface trap density.
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George, David Ray. "Fabrication of Photonic Crystal Templates through Holographic Lithography and Study of their Optical and Plasmonic Properties in Aluminium Doped Zinc Oxide." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1011779/.
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This dissertation focuses on two aspects of integrating near-infrared plasmonics with electronics with the intent of developing the platform for future photonics. The first aspect focuses on fabrication by introducing and developing a simple, single reflective optical element capable of high–throughput, large scale fabrication of micro- and nano-sized structure templates using holographic lithography. This reflective optical element is then utilized to show proof of concept in fabricating three dimensional structures in negative photoresists as well as tuning subwavelength features in two dimensional compound lattices for the fabrication of dimer and trimer antenna templates. The second aspect focuses on the study of aluminum zinc oxide (AZO), which belongs to recently popularized material class of transparent conducting oxides, capable of tunable plasmonic capabilities in the near-IR regime. Holographic lithography is used to pattern an AZO film with a square lattice array that are shown to form standing wave resonances at the interface of the AZO and the substrate. To demonstrate device level integration the final experiment utilizes AZO patterned gratings and measures the variation of diffraction efficiency as a negative bias is applied to change the AZO optical properties. Additionally efforts to understand the behavior of these structures through optical measurements is complemented with finite difference time domain simulations.
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Ahmed, Omer. "Tribological and Mechanical properties of Multilayered Coatings." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1501763970144729.
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Köhl, Dominik [Verfasser]. "The influence of energetic bombardment on the structure formation of sputtered zinc oxide films : development of an atomistic growth model and its application to tailor thin film properties / Dominik Köhl." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2011. http://d-nb.info/1018218637/34.
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Charpentier, Coralie. "Investigation of deposition conditions and annealing treatments on sputtered ZnO:Al thin films : Material properties and application to microcristalline silicon solar cells." Phd thesis, Ecole Polytechnique X, 2012. http://tel.archives-ouvertes.fr/tel-00796955.
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La couche mince d'Oxyde Transparent Conducteur (OTC) utilisée en tant qu'électrode avant pour les cellules photovoltaïques silicium microcristallin est un matériau déterminant pour l'amélioration de leur rendement. Un OTC prometteur est l'oxyde de zinc dopé aluminium ZnO:Al déposé par pulvérisation cathodique magnétron RF. Une première partie du travail de thèse est dédiée à l'étude de l'influence des conditions de dépôt sur la microstructure, les mécanismes de croissance et les propriétés optoélectroniques du ZnO:Al. Nous avons ainsi obtenu un optimum en termes de transparence maximale dans le domaine visible et de résistivité minimale pour un dépôt réalisé à une pression de 0.12 Pa pour une température de 325 °C. Une seconde partie du travail de thèse porte sur l'effet de traitements après-dépôt, recuit thermique ou laser excimère, sur les propriétés du ZnO:Al déposé à température ambiante. L'influence de différentes atmosphères (sous-vide, N2/H2, et pur N2) et températures de recuit (de 400 à 500 °C) a été étudié. L'étape de recuit thermique a permis une amélioration notable des propriétés optoélectroniques de la couche ZnO:Al, jusqu'à une résistivité de 3.5×10-4 Ohm.cm pour une transmittance entre 400 et 1000 nm de 81.2%. L'étape de recuit laser, quant à elle, influe notamment les propriétés morphologiques du matériau. L'étape finale de ce travail de thèse est basée sur l'étude de la texturation chimique, étape ayant pour but la formation d'une morphologie de surface optimale, c'est-à-dire permettant le piégeage optique dans les couches actives silicium microcristallin et ce, sans altérer les qualités électriques de la couche. L'intégration de ces couches minces ZnO:Al en tant qu'électrode avant dans des cellules photovoltaïques PIN à base de silicium microcristallin à été et étudié en détail.
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Demiroglu, Ilker. "Effect of Dimensionality and Polymorphism on the properties of ZnO." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/277286.
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Throughout this thesis, we have studied ZnO and its properties in a bottom-up manner through a dimensionality range starting from 0D nanoparticles to 3D bulk phases. For the 0D clusters and the 2D nanofilms studied we also considered the effect of a support in models designed to study ZnO thin film growth on the Ag(111) surface.
In chapter 3, we have studied ZnO nanoclusters on a Ag support and compared their properties with free space ZnO nanoclusters. In this chapter we highlighted the importance of the presence of the support during the global optimization of the clusters (i.e. as opposed to global optimization of the clusters in free space and then introducing a support). Our results show that the presence of the support strongly affects the energetic stability ranking of the nanocluster isomers. More drastically, after a certain cluster size, the support also stabilizes selectively 2D type structures, which are not stable in free space, with respect to the 3D clusters. The extra stabilization of supported 2D clusters is attributed mainly to the contact area, which is evidently greater for 2D clusters where all the atoms can interact with the surface. The importance of the contact are is also observed for 3D clusters, as ellipsoid bubbles or inflated double layer clusters being of lower energy than more spherical clusters on the support whereas the latter, more symmetric 3D clusters are more stable in free space. Matching of the cluster structure with the surface morphology was found to be another factor determining cluster stability. The Zn3O3 sixmembered ring, which is one of the main motifs for both 3D and 2D clusters, matches best with the Ag(111) surface because it follows the same six-fold (C6) symmetry (or its trigonal C3 subgroup with a three-fold axis, taking into account the distinction between Zn and O atoms). However because of the lattice size differences, such matching dies away for larger ZnO clusters. The preferential stabilities of the 2D structures of ZnO clusters can be seen as the initial stages of thin film growth and is found to be in line with the experimentally observed layered ZnO sheets on the Ag(111) surface.
In Chapter 4, we have considered a full 2D-ZnO sheet on Ag(111) surface and also investigated also how H atoms interact with it. Following our results for ZnO nanoclusters on the Ag surface, we highlighted the importance of the degree of 2D-ZnO:Ag(111) unit cell commensurability for calculating accurate sheeton-substrate binding energies. We have found a 8:9 commensurate monolayer to be more favored with interatomic potentials and a 7:8 commensurate monolayer with DFT calculations, where the latter is found in experiment. Our calculations showed no evidence of charge transfer or covalent bonding between the Ag(111) surface and the 2D-ZnO sheet, but did show that the ZnO sheet and the Ag(111) surface exhibit small structural distortions in order to maximize their mutual interaction. Calculations of the unsupported 2D-ZnO sheet interacting with hydrogen provided strong evidence for H forming a low energy Zn 4s–H 1s multi center bonding state when passing through a Zn3O3ring of the 2D-ZnO sheet, thus allowing for relatively facile H transport through the sheet.
In chapter 5, we have extended our study of supported 2D ZnO nanofilms with higher coverage models, including triangular islands on top of two full monolayers, prepared to model the experimental system. Our results showed that the triangular adlayer islands induce a transition to the WZ structure in the island core and in local region in the two layers immediately below the island core. The islands are also found to have BCT-structured reconstructions on their edges and T1-structured reconstructions on their corners. These models are found to better match the experimental structural data for the experimental 2.7 ML Ag-supported ZnO film with respect to models assuming a purely layered or a purely WZ structure.
In chapter 6, we focused on 4ML nanofilms and compared bulk and the 4 ML nanofilm poymorphism of ZnO. Our results revealed that the stability range of nanofilms and their energetic ordering are radically different than that of bulk polymorphs. We have developed a method to generate a wide range of new low energy nanofilm and bulk polymorphs using nets as a basis, and showed that there exist at least three nanofilm structures with trigonal basal plane symmetry compatible epitaxial growth on fcc metal (111) surfaces that are more stable than layered-ZnO. While confirming the previous theoretical studies predicting the BCT-ZnO phase as being the lowest energy free-standing nanofim for small thicknesses, we obtained a range of structurally related and near energetically degenerate phases, indicating there exists BCT polytypism. With increasing thickness we found that atomically reconstructed wz-ZnO becomes more stable than BCT-ZnO for ~14 MLs, and is always more stable than non-reconstructed wz-ZnO. We have also stressed the influence of strain on polymorphism by showing that BCT-ZnO and layered-ZnO nanofilms are unstable to novel polymorphs under in-plane strain. Together with the T1 structures and BCT structures which were also predicted as reconstructions on island corners in the previous chapter, our results strongly suggest that many new nanofilm polymorphs should be experimentally accessible, and in some cases, may have even already been observed.
In chapter 7, we focused on bulk polymorphism and, specifically, investigated the effect of nanoporosity. Our results showed that both energetic instability and band gap increase with nanoporosity and we predicted that nanoporosity could induce band gap increases of up to ~1.5 eV relative to wurtzite ZnO. We showed that the band gap increase is related with bandwidth changes in the conduction band and the valance band. We suggested that the underlying physical mechanism for this effect is that introducing nanoporosity, and thus periodic internal void space, restricts extended orbital overlaps and thus decreases bandwidths. Due to the generality of this argument, we expect that nanoporosity could similarly affect bandgap values in a wide range of materials and could be employed as a band gap engineering method.El treball de recerca desenvolupat en aquesta tesi es centra en ZnO, un dels semiconductors de tipus II-VI amb un ampli ventall d’aplicacions. En les estructures (ZnO)n suportades, s’observa que la presència del suport afecta l’ordre d’estabilitats dels mateixos però de manera molt més dràstica afecta selectivament les estructures bidimensionals (2D) que, a partir d’una certa grandària, en fase gas són menys estables que les tridimensionals (3D). Els càlculs per a la làmina 2D-ZnO aïllada interaccionant amb l’hidrogen proporcionen una forta evidència per a la formació d’un estat d’enllaços multi-centres de baixa energia quan passa a través de l’anell de Zn3O3 de la làmina 2D-ZnO, permetent així de forma relativament fàcil el transport d’hidrogen a través de la làmina. Quan canviem a models amb illes mes grans, observem reconstruccions estructurals a l’interior i sota l’illa formada per una nova capa incompleta. L’interior de les illes triangulars adopta estructura WZ i esta rodejada per vores amb estructures BCT i cantonades amb estructura T1. S’ha observat que aquests models presenten en un millor acord estructural amb les dades experimentals per el cas de les lamines formades per 2.7 ML que no pas respecte als models que assumeixen una estructura purament grafítica o purament WZ. Hem generat un ampli rang de polimorfs de ZnO basats en lamines hexagonals inspirades en l’enumeració de les seves xarxes subjacents característiques i evaluant l’estabilitat del sòlid “bulk” i les nano-lamines d’aquestes estructures mitjançant calculs ab initio. Hem observat un ampli polimorfisme d’estructures de baixa energia en les nano-lamines amb un ordre d’estabilitat totalment diferent al del sòlid “bulk”. A partir d’aquestes bases generals hem pogut tenir un millor coneixement de les transicions estructurals observades durant el creixement epitaxial i les prediccions d’estabilitat de les nano-lamines en variar-ne el gruix i la pressió exercida. Hem conclòs els nostres resultats explicant que la nanoporositat està inextricablement connectada tant amb la Erel com amb el ΔEgap i hem predit que la nanoporositat pot induir un increment en el band gap de fins a ~1.5 eV relatius a la wurtzita ZnO. Comprovant també la generalitat d’aquest fenomen, pe’l CdS i pel CdSe suggerim que la nanoporositat pot ser emprada com un mètode genèric d’enginyeria de band gap per materials funcionals morfològicament i electrònicament.
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Teran-Escobar, Gerardo, David M. Tanenbaum, Eszter Voroshazi, Martin Hermenau, Kion Norrman, Matthew T. Lloyd, Yulia Galagan, et al. "On the stability of a variety of organic photovoltaic devices by IPCE and in situ IPCE analyses – the ISOS-3 inter-laboratory collaboration." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-139279.
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This work is part of the inter-laboratory collaboration to study the stability of seven distinct sets of state-of-the-art organic photovoltaic (OPV) devices prepared by leading research laboratories. All devices have been shipped to and degraded at RISØ-DTU up to 1830 hours in accordance with established ISOS-3 protocols under defined illumination conditions. In this work, we apply the Incident Photon-to-Electron Conversion Efficiency (IPCE) and the in situ IPCE techniques to determine the relation between solar cell performance and solar cell stability. Different ageing conditions were considered: accelerated full sun simulation, low level indoor fluorescent lighting and dark storage. The devices were also monitored under conditions of ambient and inert (N2) atmospheres, which allows for the identification of the solar cell materials more susceptible to degradation by ambient air (oxygen and moisture). The different OPVs configurations permitted the study of the intrinsic stability of the devices depending on: two different ITO-replacement alternatives, two different hole extraction layers (PEDOT:PSS and MoO3), and two different P3HT-based polymers. The response of un-encapsulated devices to ambient atmosphere offered insight into the importance of moisture in solar cell performance. Our results demonstrate that the IPCE and the in situ IPCE techniques are valuable analytical methods to understand device degradation and solar cell lifetimeDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Teran-Escobar, Gerardo, David M. Tanenbaum, Eszter Voroshazi, Martin Hermenau, Kion Norrman, Matthew T. Lloyd, Yulia Galagan, et al. "On the stability of a variety of organic photovoltaic devices by IPCE and in situ IPCE analyses – the ISOS-3 inter-laboratory collaboration." Royal Society of Chemistry, 2012. https://tud.qucosa.de/id/qucosa%3A27818.
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This work is part of the inter-laboratory collaboration to study the stability of seven distinct sets of state-of-the-art organic photovoltaic (OPV) devices prepared by leading research laboratories. All devices have been shipped to and degraded at RISØ-DTU up to 1830 hours in accordance with established ISOS-3 protocols under defined illumination conditions. In this work, we apply the Incident Photon-to-Electron Conversion Efficiency (IPCE) and the in situ IPCE techniques to determine the relation between solar cell performance and solar cell stability. Different ageing conditions were considered: accelerated full sun simulation, low level indoor fluorescent lighting and dark storage. The devices were also monitored under conditions of ambient and inert (N2) atmospheres, which allows for the identification of the solar cell materials more susceptible to degradation by ambient air (oxygen and moisture). The different OPVs configurations permitted the study of the intrinsic stability of the devices depending on: two different ITO-replacement alternatives, two different hole extraction layers (PEDOT:PSS and MoO3), and two different P3HT-based polymers. The response of un-encapsulated devices to ambient atmosphere offered insight into the importance of moisture in solar cell performance. Our results demonstrate that the IPCE and the in situ IPCE techniques are valuable analytical methods to understand device degradation and solar cell lifetime.Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Chamorro, Coral William. "Microstructure, chemistry and optical properties in ZnO and ZnO-Au nanocomposite thin films grown by DC-reactive magnetron co-sputtering." Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0253/document.
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Les matériaux composites peuvent présenter des propriétés qu'aucun des composants individuels ne présente. En outre, à l'échelle du nanomètre les nanocomposites peuvent présenter de nouvelles propriétés par rapport à l'état massif ou à des macrocomposites des mêmes composants en raison d’effets de confinement et d’effets quantiques liés à la taille. Les nanocomposites semi-conducteur/métal sont très intéressants en raison de leurs uniques propriétés catalytiques et opto-électroniques et la possibilité de les ajuster facilement. Ce travail de thèse étudie les interactions spécifiques et les propriétés physiques qui se manifestent dans les films minces de ZnO et nanocomposites ZnO-Au synthétisés par pulvérisation magnétron réactive continue. Premièrement, il est observé qu’il est possible d'ajuster les propriétés microstructurales et optiques des couches de ZnO en réglant les paramètres expérimentaux. La croissance épitaxiale de ZnO sur saphir a été réalisée pour la première fois dans des conditions riches en oxygène sans assistance thermique. En outre, une étude des propriétés optiques met en évidence la relation étroite entre les propriétés optiques et de la chimie des défauts dans les couches minces de ZnO. Un modèle a été proposé pour expliquer la grande dispersion des valeurs de gap rencontrées dans la littérature. Deuxièmement, il a été possible de révéler l'influence profonde de l'incorporation de l'or dans la matrice de ZnO sur des propriétés importantes dans des films nanocomposites. En outre, la présence de défauts donneurs (accepteurs) au sein de la matrice ZnO se permet de réduire (oxyder) les nanoparticules d’or. Ce travail de recherche contribue à une meilleure compréhension des nanocomposites semi-conducteurs/métal et révèle le rôle important de l'état de la matrice semi-conductrice et de la surface des particules pour les propriétés finales du matériauComposite materials can exhibit properties that none of the individual components show. Moreover, composites at the nanoscale can present new properties compared to the bulk state or to macro-composites due to confinement and quantum size effects. The semiconductor/metal nanocomposites are highly interesting due to their unique catalytic and optoelectronic properties and the possibility to tune them easily. This PhD work gives insight into the specific interactions and resulting physical properties occurring in ZnO and ZnO-Au nanocomposite films grown by reactive DC magnetron sputtering. The results can be summarized in two points: First, it was possible to tune the microstructural and optical properties of ZnO. Epitaxial growth of ZnO onto sapphire was achieved for the first time in O2-rich conditions without thermal assistance. Also, a study of the optical properties highlights the close relationship between the bandgap energy (E_g ) and the defect chemistry in ZnO films. A model was proposed to explain the large scatter of the E_g values reported in the literature. Second, the deep influence of the incorporation of gold into the ZnO matrix on important material properties was revealed. Moreover, the presence of donor (acceptor) defects in the matrix is found to give rise to the reduction (oxidation) of the Au nanoparticles. This research work contributes to a better understanding of semiconductor/metal nanocomposites revealing the key role of the state of the semiconductor matrix
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Yang, Zheng. "Doping in zinc oxide thin films." Diss., [Riverside, Calif.] : University of California, Riverside, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3359913.
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Thesis (Ph. D.)--University of California, Riverside, 2009.Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 12, 2010). Includes bibliographical references. Also issued in print.
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Depaz, Michael. "Processing and characterization of zinc oxide thin films." [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002235.
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Yang, Hung-Pao 1980. "A study of P-type zinc oxide thin films /." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99550.
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In the past decade, p-type ZnO material has been investigated extensively. Its properties offer the potential for broad applications including the development of ultraviolet light emitting devices. Although n-type ZnO material is well known and studied for decades, the fabrication method and properties of p-type ZnO material are still to date not clearly understood.In this report, reproducible p-type ZnO thin films sputtered on glass substrates are reported. On the same substrate, p-type ZnO film is local and surrounded by n-type ZnO regions. The thickness of the films is typically three microns after several hours of deposition by radio-frequency magnetron sputtering technique. Both p-type ZnO and n-type thin films are characterized by optical and electrical measurements at room temperature.
The crystal structure of p-type ZnO is examined by X-ray diffraction patterns. The X-ray diffraction patterns show that the material is polycrystalline and has (100) and (101) preferred orientation. Photoluminescence spectra of ZnO help to identify the energy levels in the material and spectra analysis reveals the presence of defects and dopants in the material. For p-type ZnO, the resistivity, the hole concentration and hole mobility are found to be 148.8 O-cm, 4.34 x 1018/cm3 and 1.72 x 10-2 cm2/V-sec respectively.
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Potter, D. "Zinc-based thin films for transparent conducting oxide applications." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10041886/.
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This thesis describes the synthesis of zinc-based transparent conducting oxide (TCO) thin films, as sustainable alternatives to commercial TCOs. There are two main aims to this work. The first is the discovery of suitable TCO materials, which involves finding the optimum optoelectronic properties for applications in photovoltaic devices. The second aim is investigating the scale up of aerosol assisted chemical vapour deposition (AACVD), which is the technique used to deposit the majority of the films in this work. The films deposited in this work were characterised by X-ray diffraction (XRD) to find the crystal structures, X-ray photoelectron spectroscopy (XPS) to find the elemental compositions, scanning electron microscopy (SEM) to analyse the surface morphologies, UV/vis spectroscopy to find the optical properties, and by Hall effect measurements to find the electrical properties. Aluminium, gallium, indium, silicon, and fluorine have been examined as dopants for ZnO, in various combinations, and at different concentrations. The films were generally found to have high transparency, and electrical properties that approached those of industrial TCO materials. The merits of the films are particularly promising, when considering the relative ease through which the films were synthesised. Additionally, the effect of varying the solvent used to make up the precursor solution is investigated. The deposition of ZnSb2O6 thin films via spin coating is also discussed. This thesis also details an investigation into the scale-up of AACVD. An aerosol transport study was performed, whereby the aerosol was transported prior to deposition. It was found that a considerable amount of aerosol was condensing within the tubing, prior to reaching the reactor. Additionally, increasing the film growth rates was investigated by depositing FTO films using high concentrations in the precursor solution. Growth rates of approximately 2 μm min-1 were achieved, making the use of AACVD for commercial applications significantly more feasible.
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Choppali, Uma. "Low Temperature Polymeric Precursor Derived Zinc Oxide Thin Films." Thesis, University of North Texas, 2006. https://digital.library.unt.edu/ark:/67531/metadc5504/.
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Zinc oxide (ZnO) is a versatile environmentally benign II-VI direct wide band gap semiconductor with several technologically plausible applications such as transparent conducting oxide in flat panel and flexible displays. Hence, ZnO thin films have to be processed below the glass transition temperatures of polymeric substrates used in flexible displays. ZnO thin films were synthesized via aqueous polymeric precursor process by different metallic salt routes using ethylene glycol, glycerol, citric acid, and ethylene diamine tetraacetic acid (EDTA) as chelating agents. ZnO thin films, derived from ethylene glycol based polymeric precursor, exhibit flower-like morphology whereas thin films derived of other precursors illustrate crack free nanocrystalline films. ZnO thin films on sapphire substrates show an increase in preferential orientation along the (002) plane with increase in annealing temperature. The polymeric precursors have also been used in fabricating maskless patterned ZnO thin films in a single step using the commercial Maskless Mesoscale Materials Deposition system.
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Huang, Bin. "Mechanical characterization of thin films /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?MECH%202005%20HUANG.
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Miller, Paul. "Zinc Oxide: A spectroscopic investigation of bulk crystals and thin films." Thesis, University of Canterbury. Physics and Astronomy, 2008. http://hdl.handle.net/10092/3618.
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The optical properties of zinc oxide crystals and thin films prepared by different methods are investigated. Single crystal zinc oxide samples prepared by melt and hydrothermal growth techniques were obtained. The influence of polarity and growth method on the optical properties were studied and correlated with their electronic properties. Thin films prepared by molecular beam epitaxy (MBE) and sputtering were studied and the influence of growth conditions and post growth treatment on the optical properties of the films was investigated. The photo-luminescence (PL) of bulk zinc oxide was examined at high resolution. Line widths of less than 0.1 meV were observed. More than a dozen different transitions in the near band edge region (NBE 360-380 nm) were noted, several of which displayed a separation of <0.5 meV which goes some way to illustrating the complexity of the system. Attempts were made, with some success, to reconcile the two main competing identification systems of the NBE transitions and explanations for some of the discrepancies are provided. The controversial deep level transitions in the visible part of the spectrum are fit with 3 Gaussians and their identities discussed with relation to the available literature. The presence of copper impurities was detected in annealed films and a model to explain their behaviour under annealing conditions is hypothesised. Films grown by MBE here at the University of Canterbury are shown to have PL line widths of as little as 2.2 meV, the ratio of active oxygen species in the growth chamber during deposition is shown to effect the optical quality of the films. It is shown that annealing can improve the optical quality of the films and various other methods of influencing the films properties are discussed. Reactive, magnetron, direct current sputtering is shown to be the optimal method of growth for maximising both optical and piezo-electric properties. Optimum annealing temperatures were found at 900 and 1100 ℃ with a local minimum at 1000 ℃. X-ray diffraction, atomic force and scanning electron microscopy measurements in addition to optical PL measurements show the influence of annealing on the polycrystalline sputtered ZnO films. Films grown on glass, silicon, sapphire and quartz were shown to display similar behaviour under annealing conditions. It was found that zinc oxide based devices were liable to be chemically unstable at temperatures above 1100 ℃. The piezo electric properties of the films were examined and attempts were made to prepare a zinc oxide film optimised for both optical quality and piezoelectric properties for possible future applications of a hybrid opto-mechanical coupled devices.
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Zhang, Rong. "Zinc Oxide Thin Films for Dye-Sensitized Solar Cell Applications." Miami University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=miami1186016777.
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Backholm, Jonas. "Electrochromic Properties of Iridium Oxide Based Thin Films." Doctoral thesis, Uppsala universitet, Fasta tillståndets fysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8505.
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Electrochromic iridium oxide (IrOx) and iridium-tantalum oxide (IrTaOx) thin films were prepared by reactive magnetron sputtering. Composition, density, and structure were determined using Rutherford backscattering spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and electron energy loss spectroscopy. The electronic density of states (DOS) and the solid phase chemical diffusion coefficient (D) were determined for hydrogen in IrOx and IrTaOx by potentiostatic intermittent titration technique (PITT), and electrochemical impedance spectroscopy (EIS). The complex refractive indices were determined for colored and bleached IrOx and IrTaOx by inverting transmission and reflectance, measured using spectrophotometry in the 300-2500 nm wavelength range. A very porous structure, with a stoichiometry of IrO2.2, was found for IrOx. It contained ~4 nm sized grains. The IrTaOx had a denser structure built up by ~4 nm sized grains. The composition of IrTaOx was found to vary on a nanometer scale, with an average composition of IrTa1.4O5.6. It was found that DOS can be measured using PITT and EIS in the presence of spontaneous side reactions, even for systems influenced by non-negligible charge transfer kinetics and Ohmic drops. It was found that the measured DOS is 30-50% of the theoretically calculated DOS and that D is in the 10-10 – 10-11 cm2/s range for both materials. The hydrogen diffusion mechanism was described by an anomalous diffusion model, possibly indicating percolation or diffusion paths described by a fractal network. The refractive indices were found to be ~1.3 and ~2 for IrOx and IrTaOx, respectively, and independent of coloration state, whereas the extinction coefficients were found to modulate by ~30% for IrOx and ~50% for IrTaOx, making IrTaOx more favorable for electrochromic applications. A modulation peak was found at ~660 nm for both IrOx and IrTaOx associated with the removal of intraband transitions within the Ir t2g band.
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Murphy, Thomas Patrick. "Electrochromic properties of tin-nickel oxide thin films." Thesis, Oxford Brookes University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284756.
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Hilou, H. W. "Electrical properties of R.F. sputtered thin oxide films." Thesis, University of Nottingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355425.
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Rauf, Ijaz Ahmad. "Structure and properties of indium oxide thin films." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358371.
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Hong, Yuanjia. "Magnetic and Transport Properties of Oxide Thin Films." ScholarWorks@UNO, 2007. http://scholarworks.uno.edu/td/615.
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My dissertation research focuses on the investigation of the transport and magnetic properties of transition metal and rare earth doped oxides, particularly SnO2 and HfO2 thin films. Cr- and Fe-doped SnO2 films were deposited on Al2O3 substrates by pulsed-laser deposition. Xray- diffraction patterns (XRD) show that the films have rutile structure and grow epitaxially along the (101) plane. The diffraction peaks of Cr-doped samples exhibit a systematic shift toward higher angles with increasing Cr concentration. This indicates that Cr dissolves in SnO2. On the other hand, there is no obvious shift of the diffraction peaks of the Fe-doped samples. The magnetization curves indicate that the Cr-doped SnO2 films are paramagnetic at 300 and 5 K. The Fe-doped SnO2 samples exhibit ferromagnetic behaviour at 300 and 5 K. Zero-field-cooled and field-cooled curves indicate super paramagnetic behavior above the blocking temperature of 100 K, suggesting that it is possible that there are ferromagnetic particles in the Fe-doped films. It was found that a Sn0.98Cr0.02O2 film became ferromagnetic at room temperature after annealing in H2. We have calculated the activation energy and found it decreasing with the annealing, which is explained by the increased oxygen vacancies/defects due to the H2 treatment of the films. The ferromagnetism may be associated with the presence of oxygen vacancies although AMR was not observed in the samples. Pure HfO2 and Gd-doped HfO2 thin films have been grown on different single crystal substrates by pulsed laser deposition. XRD patterns show that the pure HfO2 thin films are of single monoclinic phase. Gd-doped HfO2 films have the same XRD patterns except that their diffraction peaks have a shift toward lower angles, which indicates that Gd dissolves in HfO2. Transmission electron microscopy images show a columnar growth of the films. Very weak ferromagnetism is observed in pure and Gd-doped HfO2 films on different substrates at 300 and 5 K, which is attributed to either impure target materials or signals from the substrates. The magnetic properties do not change significantly with post deposition annealing of the HfO2 films.
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Ali, Arshid Mahmood. "Characterisation of semi-conductor zinc oxide (ZnO) thin films as photocatalysts." Thesis, University of Auckland, 2011. http://hdl.handle.net/2292/7203.
Full textAbstract:
The objective of this project was to study the suitability of nanostructured ZnO thin films as efficient photocatalysts and to characterise any issues that may be involved in the scale-up of photocatalytic systems based on these types of immobilised nanostructure ZnO thin films. In particular, this study involved fabricating and then evaluating the effectiveness of a range of nanostructured zinc oxide (ZnO) thin films with different structures and chemistries (i.e. undoped and doped) as photocatalysts, and thereafter to systematically relate: the initial and reacted surface morphology; photocatalytic activity in terms of reaction rate; reaction intermediates and products; and liquid phase and solid phase reaction mechanisms under both limited and rich oxygen conditions at two different UV irradiation wavelengths (254nm and 340nm). These nanostructured thin films (i.e. undoped ZnO; nitrogen doped ZnO - N:ZnO; cobalt doped ZnO - Co:ZnO) were produced using an innovative combination of magnetron sputtered surfaces and hydrothermal solution deposition that allows the morphology, porosity and thickness to be controlled by varying the composition and processing conditions. SEM, UV-Vis, HPLC, LC-MS, AAS and XRD were used to study the changes in thin film morphology, Methylene Blue (MB) degradation and its reaction intermediates, the presence of Zn metal in the reaction fluid, if any, and crystallinity before and after the photocatalytic reaction respectively. Undoped ZnO thin films: Results showed a clear relationship between surface morphology (and the related thin film preparation method) and photocatalytic activity for the ZnO thin film supported catalysts: the tallest, most aligned structure had the highest photocatalytic activity, whilst the smallest, least aligned structure had the lowest. Thus, the MB degradation rate was the fastest for the ZnO thin film (S2-MS) with a uniform arrayed structure. Adding oxygen made the films more stable: in oxygen-limited conditions, SEM and atomic absorption spectroscopy indicated zinc leaching had occurred. Furthermore, with additional oxygen the zinc leaching was minimised under the same reaction conditions. It is thought that this additional oxygen is either minimising the release of, or replacing lost ZnO lattice oxygens, indicating that this ZnO photocatalytic oxidation could be occurring via a Mars van Krevelen type redox mechanism. There was also a significant difference in MB degradation rates, as well as reaction intermediate formation and destruction rates, correlated to the morphologies and crystallinity at both UV wavelengths, with the highest reaction rates at 340nm. Reaction analysis indicates that there is a competition between two different photocatalytic mechanisms: conventional photocatalysed radical oxidation and lattice oxygen-driven oxidation. The dominant reaction mechanism depends on the thin film morphology, crystallinity, availability of oxidant and the wavelength of the incident UV. The surface-photocatalysed radical formation was predominant for more aligned, highly crystalline, morphologies, where there was plentiful oxygen and UV irradiation at 340nm. Lattice oxygen photodegradation was predominant for the less aligned, more amorphous morphologies and UV irradiation at 254nm. Doped (Co:ZnO) thin films: Results showed that cobalt dopant increases the photo-stability of the corresponding undoped thin films under oxygen-limited conditions - increasing with the increased dopant concentration. This increased stability of Co:ZnO nanostructure thin films comes with a price, however: the photocatalytic activity and concomitant degradation of MB and its azo dyes reaction intermediates is in general lowered, compared to the undoped ZnO thin films. At higher dopant concentrations, under oxygen-rich conditions and with UV irradiation at 254nm and 340nm, the MB degradation most likely occurs via a conventional photocatalytic reaction mechanism and/or via charge transfer of the MB into Azure B (AB) with the absence of Mars van Krevelen type mechanism (because of the increased lattice stability). At lower dopant concentrations under oxygen-limited conditions with UV irradiation at 254nm and 340nm, the Mars van Krevelen type reaction mechanism is probably the main mechanism propagating the oxidation of MB. Overall, the undoped morphologies were more photocatalytically active compared to the doped morphologies. In general, this work has shown that several different solid and liquid phase photocatalytic reaction mechanisms govern the photocatalytic degradation of azo dyes such as MB on nanostructured ZnO thin films, and that surface morphology, crystallinity, lack or presence of oxygen, and the dopant concentration are the key parameters governing the overall photocatalytic activity and the activation of these different solid and liquid photocatalytic reaction mechanisms.
41
Weigand, Christian Carl. "Zinc Oxide Nanostructures and Thin Films Grown by Pulsed Laser Deposition." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elektronikk og telekommunikasjon, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18268.
Full textAbstract:
ZnO nanostructures have received great attention during the past decade due to numerous potential applications. In order to enable the fabrication of functional devices, reproducible preparation of such nanostructures is necessary. Therefore, a good understanding of the fundamental processes involved in the formation of ZnO nanostructures is indispensable for improving the controllability of nanostructure growth. This work elucidates various aspects of the essential nucleation and growth mechanisms at work during the growth of ZnO nanostructures by catalyst-assisted pulsed laser deposition (PLD). ZnO nanowires and triangular nanosheets have been grown on sapphire substrates by Auassisted PLD. In a first study, the influence of thermal substrate pretreatments on the size and density of the ZnO nanostructures is investigated. It has been found that the presence of surface nucleation sites can compete with nucleation at the Au catalyst and lead to reduced nanostructure sizes and densities. Furthermore, it has been observed that the ZnO morphology switches from nanowires to triangular nanosheets upon increasing oxygen partial pressure in the growth chamber. Electron microscopy results indicates that the catalyst-nanowire growth interface plays an important role in this morphology change. Formation mechanisms of the two different nanostructure types are presented and possible links between oxygen pressure and morphology via growth kinetics and supersaturation considerations are discussed. Additionally, the epitaxial relationships between the two ZnO nanostructure types and sapphire substrates have been investigated in detail by combining x-ray pole figure measurements with both transmission and scanning electron microscope observations. ZnO nanowires growing tilted on c-plane sapphire showed an epitaxial alignment with a buried and inclined substrate plane. Two degenerate configurations have been identified for these tilted wires, promoted by equally low lattice mismatches. On a-plane sapphire, ZnO nanosheets and -wires show distinct differences in the epitaxial relationships with the substrate, indicating a direct correlation to the morphology. The findings about ZnO nanostructures presented in this thesis help to improve control over catalyst-assisted nanostructure growth techniques and provide a further step towards reproducible nanostructure fabrication. In a second part of the thesis, the electrical and optical properties of Al-doped ZnO (AZO) thin films grown on GaAs substrates by PLD have been investigated. AZO is a promising candidate for substituting indium tin oxide as transparent electrodes in optoelectronic applications. The aim of the study is to assess the suitability of AZO as a transparent electrode shell around GaAs nanowire solar cells for direct charge carrier pathways. Furthermore, the portability of previously reported results obtained on transparent substrates such as glass or sapphire to the opaque GaAs substrate is discussed.
42
Wellenius, Patrick. "Nitrogen Doping and Ion Beam Processing of Zinc Oxide Thin Films." NCSU, 2006. http://www.lib.ncsu.edu/theses/available/etd-01042006-015801/.
Full textAbstract:
The modification of single crystal epitaxial ZnO thin films grown by Pulsed Laser Deposition on c-axis oriented sapphire substrates by Ion Beam Processing was investigated. Nitrogen doping of the films was attempted using nuclear transmutation using the 16O (3He, 4He) 15O reaction at 6.6 MeV. The 15O product is unstable and decays to 15N after several minutes by positron emission. There are several potential advantages to using nuclear transmutation including producing nitrogen atoms on the correct lattice site for doping and reduced crystal damage as compared to conventional ion beam implantation. In the experiments in this thesis the doping levels achieved ~1014 cm-3 were too low to be expected to dope the films to p-type. However several beneficial effects due to the ion beam processing were observed, including large increases in resistivity, reduction of defect luminescence, and substantial increases in the response of photoconductive detectors. In addition to desired effects in some films it was also found that in some films bubble like structures approximately 10 ìm in diameter were formed where the thin film delaminated from the surface. It was assumed that mechanism for the bubble formation was the build up of helium gas at the sapphire/ZnO interface.
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Kekuda, Dhananjaya. "Property Modulation Of Zinc Oxide Through Doping." Thesis, 2007. https://etd.iisc.ac.in/handle/2005/465.
Full textAbstract:
Semi conductors are of technological importance and attracted many of the re-searchers. ZnO belongs to the family of II-VI semiconductors and has material properties well suitable to UV light emitters, varistors, Schottky diodes, gas sensors, spintronics, ferroelectric devices and thin film transistors. It has been considered as a competitor to GaN, which belongs to the family of III-V semiconductors. This is due to the fact that ZnO of high quality can be deposited at lower growth temperatures than GaN, leading to the possibility of transparent junctions on less expensive substrates such as glass. This will lead to low-cost UV lasers with important applications in high-density data storage systems etc. One of the most popular growth techniques of ZnO is physical sputtering. As compared to sol-gel and chemical-vapor deposition, the magnetron sputtering is a preferred method because of its simplicity and low operating temperatures. Hence, detailed investigations were carried out on undoped and doped ZnO thin films primarily deposited by magnetron sputtering. The obtained results in the present work are presented in the form of a thesis.
Chapter 1: A brief discussion on the crystal structure of ZnO material and its possible applications in the different areas such as Schottky diodes, spintronics, ferroelectric devices and thin film transistors are presented.
Chapter 2: This chapter deals with various deposition techniques used in the present study. It includes the magnetron sputtering, thermal oxidation, pulsed-laser ablation and sol-gel technique. The experimental set up details and the deposition procedures are described in detail i.e., the deposition principle and the parameters that will affect the film properties. A brief note on the structural characterization equipments namely, X-ray diffraction, scanning electron microscopy, atomic force microscopy, transmission electron microscopy and the optical characterization equipments namely, transmission spectroscopy is presented. The transport properties of the films were studied which include Dielectric studies, impedance studies, device characterization and are discussed.
Chapter 3: The optimization of ZnO thin films for Schottky diode formation and
The characterization of various Schottky diodes is presented in this chapter. P-type conductivity in ZnO was implemented by the variation of partial pressure of oxygen during the sputtering and are discussed. A method to achieve low series resistance hetero-junction was achieved using thermal oxidation method and the detailed transport properties were studied. The optical investigation carried out on the ZnO thin films under various growth conditions are also presented.
Chapter 4: This chapter deals with the processing, structural, electrical, optical and magnetic properties of Mn doped ZnO thin films grown by pulsed laser ablation. Structural investigations have shown that the Mn incorporation increases the c-axis length due to the relatively larger ionic size of the Mn ions. Studies conducted both at low and high concentration region of Zn1¡xMnxO thin films showed that the films are anti-ferromagnetic in nature. The transport measurements revealed that the electrical conductivity is dominated by the presence of shallow traps. Optical investigations suggested the absence of midgap absorption and confirm the uniform distribution of Mn in wurtzite structure.
Chapter 5: Carrier induced ferromagnetism in Co doped ZnO thin films were studied and the results are presented in this chapter. High density targets were prepared by solid state reaction process and the thin films were deposited by pulsed laser ablation technique. Two compositions were studied and it was found that with increase in substrate temperature, c-axis length decreases. Optical studies suggested a strong mid gap absorption around 2eV and could be attributed to the d-d transitions of tetrahedral coordinated Co2+. The presence of ferromagnetism in these films makes them potential candidates for spintronics applications.
Chapter 6: It has been reported in literature that o®-centered polarization will drive ferroelectric phase transition. Motivated by such results, substitution of Lithium in ZnO was studied in detail. The structural and electrical properties were investigated over a wide range of composition (0-25%). The ferroelectric studies were carried out both in metal-insulator-metal (MIM) and metal-insulator-semiconductor (MIS) configuration and are presented in this chapter. The appearance of Ferro electricity in these films makes them potential candidates for ferroelectric memory devices.
Chapter 7: This chapter describes the studies conducted on Mg doped ZnO
Thin films grown by multi-magnetron sputtering. The hexagonal phases of the films were evaluated. All the films exhibited c-axis preferred orientation towards (002) orientation. Micro structural evolutions of the films were carried out through scanning electron microscopy and atomic force microscopy. Ferroelectric properties were investigated in both metal-insulator-metal (MIM) and metal-insulator-semiconductor (MIS) configurations. It was observed that the Mg concentration increases the band gap and the details on optical investigations are also presented in this chapter.
Chapter 8: ZnO based thin film transistors have been fabricated and characterized using ZnO as active channel layer and Mg doped ZnO as dielectric layer. Excellent leakage properties of the gate dielectric were studied and presented in this chapter. These studies demonstrated that Mg doped ZnO thin films are suitable candidates for gate dielectric applications.
Conclusions: This section presents the conclusions derived out of the present work. It also includes a few suggestions on future work on this material.
44
Kekuda, Dhananjaya. "Property Modulation Of Zinc Oxide Through Doping." Thesis, 2007. http://hdl.handle.net/2005/465.
Full textAbstract:
Semi conductors are of technological importance and attracted many of the re-searchers. ZnO belongs to the family of II-VI semiconductors and has material properties well suitable to UV light emitters, varistors, Schottky diodes, gas sensors, spintronics, ferroelectric devices and thin film transistors. It has been considered as a competitor to GaN, which belongs to the family of III-V semiconductors. This is due to the fact that ZnO of high quality can be deposited at lower growth temperatures than GaN, leading to the possibility of transparent junctions on less expensive substrates such as glass. This will lead to low-cost UV lasers with important applications in high-density data storage systems etc. One of the most popular growth techniques of ZnO is physical sputtering. As compared to sol-gel and chemical-vapor deposition, the magnetron sputtering is a preferred method because of its simplicity and low operating temperatures. Hence, detailed investigations were carried out on undoped and doped ZnO thin films primarily deposited by magnetron sputtering. The obtained results in the present work are presented in the form of a thesis.
Chapter 1: A brief discussion on the crystal structure of ZnO material and its possible applications in the different areas such as Schottky diodes, spintronics, ferroelectric devices and thin film transistors are presented.
Chapter 2: This chapter deals with various deposition techniques used in the present study. It includes the magnetron sputtering, thermal oxidation, pulsed-laser ablation and sol-gel technique. The experimental set up details and the deposition procedures are described in detail i.e., the deposition principle and the parameters that will affect the film properties. A brief note on the structural characterization equipments namely, X-ray diffraction, scanning electron microscopy, atomic force microscopy, transmission electron microscopy and the optical characterization equipments namely, transmission spectroscopy is presented. The transport properties of the films were studied which include Dielectric studies, impedance studies, device characterization and are discussed.
Chapter 3: The optimization of ZnO thin films for Schottky diode formation and
The characterization of various Schottky diodes is presented in this chapter. P-type conductivity in ZnO was implemented by the variation of partial pressure of oxygen during the sputtering and are discussed. A method to achieve low series resistance hetero-junction was achieved using thermal oxidation method and the detailed transport properties were studied. The optical investigation carried out on the ZnO thin films under various growth conditions are also presented.
Chapter 4: This chapter deals with the processing, structural, electrical, optical and magnetic properties of Mn doped ZnO thin films grown by pulsed laser ablation. Structural investigations have shown that the Mn incorporation increases the c-axis length due to the relatively larger ionic size of the Mn ions. Studies conducted both at low and high concentration region of Zn1¡xMnxO thin films showed that the films are anti-ferromagnetic in nature. The transport measurements revealed that the electrical conductivity is dominated by the presence of shallow traps. Optical investigations suggested the absence of midgap absorption and confirm the uniform distribution of Mn in wurtzite structure.
Chapter 5: Carrier induced ferromagnetism in Co doped ZnO thin films were studied and the results are presented in this chapter. High density targets were prepared by solid state reaction process and the thin films were deposited by pulsed laser ablation technique. Two compositions were studied and it was found that with increase in substrate temperature, c-axis length decreases. Optical studies suggested a strong mid gap absorption around 2eV and could be attributed to the d-d transitions of tetrahedral coordinated Co2+. The presence of ferromagnetism in these films makes them potential candidates for spintronics applications.
Chapter 6: It has been reported in literature that o®-centered polarization will drive ferroelectric phase transition. Motivated by such results, substitution of Lithium in ZnO was studied in detail. The structural and electrical properties were investigated over a wide range of composition (0-25%). The ferroelectric studies were carried out both in metal-insulator-metal (MIM) and metal-insulator-semiconductor (MIS) configuration and are presented in this chapter. The appearance of Ferro electricity in these films makes them potential candidates for ferroelectric memory devices.
Chapter 7: This chapter describes the studies conducted on Mg doped ZnO
Thin films grown by multi-magnetron sputtering. The hexagonal phases of the films were evaluated. All the films exhibited c-axis preferred orientation towards (002) orientation. Micro structural evolutions of the films were carried out through scanning electron microscopy and atomic force microscopy. Ferroelectric properties were investigated in both metal-insulator-metal (MIM) and metal-insulator-semiconductor (MIS) configurations. It was observed that the Mg concentration increases the band gap and the details on optical investigations are also presented in this chapter.
Chapter 8: ZnO based thin film transistors have been fabricated and characterized using ZnO as active channel layer and Mg doped ZnO as dielectric layer. Excellent leakage properties of the gate dielectric were studied and presented in this chapter. These studies demonstrated that Mg doped ZnO thin films are suitable candidates for gate dielectric applications.
Conclusions: This section presents the conclusions derived out of the present work. It also includes a few suggestions on future work on this material.
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van, Heerden Johannes Lodewikus. "Material properties of ZnO thin films prepared by spray pyrolysis." Thesis, 2012. http://hdl.handle.net/10210/6033.
Full textAbstract:
Ph.D.In the search to improve the conversion efficiency of solar cells such as α-Si and CuInSe2 cells, attention have recently been focused on the use of transparent conducting oxides (TCO's) as window layers and top electrodes in these cells. Materials such as indium tin oxide (ITO) and fluorine-doped tin oxide (FTO) thin films were used due to their excellent electro-optical properties, but it was found that they were unstable when subjected to a hydrogen plasma (during the a-Si deposition) and that the materials reduced to their metallic forms, degrading their electrical and optical properties. Zinc oxide (ZnO), however, possess electrical and optical properties equal to ITO and FTO, but is stable in the presence of a hydrogen plasma. In this study a system for the deposition of ZnO thin films by spray pyrolysis was developed and the films successfully deposited. The films were also doped with A1C1 3 in an attempt to further improve the films' conductivities. The films were then characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), electrical measurements (Hall and four-point probe measurements) and optical analyses of the films. The films were compared with films deposited by atomic layer epitaxy (ALE) and DC sputtering. It was found that the films were crystalline with a predominantly (002) preferred orientation. The addition of Al as dopant, however, resulted in the film structure deteriorating. The SEM micrographs obtained of the films indicated films with a close-packed structure, existing of small grains and the film surface having a textured appearance. It was further found that the deposition parameters of the films influenced both the structures of the films and the morphologies and the micrographs indicated that the addition of Al as dopant resulted in the film formation being inhibited and even resulting in no proper film being deposited. It was found that the as-deposited ZnO films were resistive and that the films had to be subjected to a post-deposition annealing to decrease the film resistivity. The annealing conditions were investigated and it was found that annealing the films in hydrogen at their deposition temperature for an hour resulted in the largest decrease in the films' resistivities, typically two orders of magnitude. Studies of the substrate temperature indicated that the films had to be deposited at between 350 and 420°C and that a reduction in the substrate temperature resulted in the film resistivity increasing. Contrary to literature, it was found that the addition of Al as dopant had no beneficial influence on the electrical properties of the films and that dopant concentrations exceeding 1.0 at.% resulted in the film resistivity increasing. The films were characterized optically by analysing the transmission spectra obtained of the films, using the envelope technique. It was found that the films had transmissions exceeding 95% and that the refractive indices and optical gaps centred around 1.99 and 3.3 eV respectively. Both properties were affected by the deposition parameters. The ZnO films deposited by spray pyrolysis compared excellently with the films prepared by ALE and DC sputtering in all aspects. It is hence clear that ZnO films, with characteristics suitable for solar cell application, can be deposited by the simple and inexpensive technique of spray pyrolysis.
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"Effects of metallization on optical properties of ZnO thin films." 2006. http://library.cuhk.edu.hk/record=b5892774.
Full textAbstract:
Lai Chung Wing = 金屬膜覆蓋在氧化鋅上之光學變化 / 黎頌榮.Thesis submitted in: July 2005.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2006.
Includes bibliographical references.
Text in English; abstracts in English and Chinese.
Lai Chung Wing = Jin shu mo fu gai zai yang hua xin shang zhi guang xue bian hua / Li Songrong.
Acknowledgements --- p.i
Abstract --- p.ii
摘要 --- p.iii
Table of contents --- p.iv
List of Figures --- p.vi
Chapter Chapter 1 --- Introduction
Chapter 1.1. --- Motivation --- p.1-1
Chapter 1.2. --- Literature Review --- p.1-2
Chapter 1.3. --- Our Study --- p.1-4
References --- p.1-6
Chapter Chapter 2 --- Methodology and Experiments
Chapter 2.1. --- RF sputtering --- p.2-1
Chapter 2.1.1. --- Setup of RF sputtering --- p.2-2
Chapter 2.1.2. --- Sample preparation --- p.2-3
Chapter 2.2. --- Scanning electron Microscope --- p.2-4
Chapter 2.3. --- Cathodoluminescence --- p.2-5
Chapter 2.3.1. --- Background of CL --- p.2-6
Chapter 2.3.2. --- Room temperature CL studies --- p.2-7
Chapter 2.3.3. --- Software: Casino --- p.2-8
Chapter 2.3.4. --- Depth resolved CL studies --- p.2-10
Chapter 2.3.5. --- Power dependent CL studies --- p.2-11
Chapter 2.4. --- Photoluminescence
Chapter 2.4.1. --- General background of PL --- p.2-11
Chapter 2.4.2. --- Room temperature PL studies --- p.2-12
Chapter 2.4.3. --- Quantum efficiency measurement --- p.2-13
Chapter 2.5. --- Optical transmission measurement --- p.2-13
References --- p.2-15
Chapter Chapter 3 --- Experimental Results and Data Analysis
Chapter 3.1. --- Study of Optical emissions of bare and Au-capped ZnO --- p.3-1
Chapter 3.1.1. --- RT-luminescence of ZnO --- p.3-1
Chapter 3.1.2. --- RT- Luminescence of Au- capped ZnO films --- p.3-2
Chapter 3.2. --- RT-luminescence of metal capped ZnO --- p.3-7
Chapter 3.3. --- Power dependent and depth Resolved CL --- p.3-10
Chapter 3.3.1. --- Dependence of the CL on beam energy --- p.3-10
Chapter 3.3.2. --- Dependence of the CL intensity on beam energy --- p.3-13
Chapter 3.4. --- Dependence of metal thickness on the RT- luminescence --- p.3-17
References --- p.3-19
Chapter Chapter 4 --- Discussions
Chapter 4.1. --- General discussions --- p.4-1
Chapter 4.2. --- Surface recombination Velocity
Chapter 4.2.1. --- Quantum Efficiency --- p.4-2
Chapter 4.2.2. --- Simulation of the dependence of surface recombination velocity on the CL intensity of ZnO --- p.4-5
Chapter 4.3. --- Effects of metallization on MgZnO/ZnO bilayer --- p.4-10
Chapter 4.4. --- Surface plasmon --- p.4-13
Chapter 4.5. --- PL measurement from the backside of substrate --- p.4-18
Chapter 4.5.1. --- Au and Ag coating by sputtering --- p.4-19
Chapter 4.5.2. --- Au and Ag coating by thermal evaporation --- p.4-21
Chapter 4.6. --- Au coating spaced by MgO --- p.4-23
Chapter 4.7. --- Optical transmission of Au-capped ZnO --- p.4-25
Chapter 4.8. --- Cross Section images by AFM and TEM --- p.4-27
Chapter 4.9. --- Application: optical improvement of semiconductor --- p.4-30
Chapter 4.10. --- Summary --- p.4-32
References --- p.4-34
Chapter Chapter 5 --- Conclusions --- p.5-1
Appendix I --- p.A
Appendix II --- p.K
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"Study of ferromagnetic and field effect properties of ZnO thin films." Thesis, 2011. http://library.cuhk.edu.hk/record=b6075123.
Full textAbstract:
Xia, Daxue.Thesis (Ph.D.)--Chinese University of Hong Kong, 2011.
Includes bibliographical references.
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.
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Ko, Chun Hsien, and 柯俊賢. "Electrical and Optical Properties of Rare Earth-Doped Zinc Oxide Thin Films." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/43554022656985473590.
Full textAbstract:
碩士國立中正大學
光機電整合工程所
96
It was mainly aspiration to prepare transparent conducting ZnO thin films co-doped with Al and Europium ion (Eu3+) / Terbium ion (Tb3+) by sol- gel method in the thesis. Film deposition was performed by spin- coating technique on a glass substrate. The characterization of electric and optical properties were measured to discuss the difference in those properties between the AZO thin films doped with rare-earth elements and the AZO thin films undoped with rare-earth elements. The best experimental condition of electrical and optical properties was obtained for the ZnO films doped with 1.5 mol.% Al. The optical transmittance spectra of the films show the transmittance higher than 85% within the visible wavelength region. For the AZO films individually doped with Europium ion and Terbium ion, a minimum resistivity of 3.36×10-4Ωcm was obtained and the transmittance is higher than 80% within the visible wavelength region. However, the higher concentration of the Europium ion or Terbium ion was, the high resistivity of the films was. It was found that the optical properties of ZnO powder co-doped with Yttrium ion (Y3+) and Europium ions were evidence in the analysis of photoluminescence spectra. The concentration of the Yttrium ion and the temperature, if the concentration of the Europium ion was 5 mol.%, was gradually higher. The optical properties of ZnO powder co-doped with Yttrium ion and Europium ion were also higher and were specifically higher at the annealing temperature of 800 °C and 900 °C. On the other hand, the intensity of photoluminescence properties of ZnO powder co-doped with Yttrium ion and Europium ion were enhanced stronger over 70% than the intensity of photoluminescence properties of ZnO powder co-doped with Europium ion.
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Hsiao, Yen-Chih, and 蕭彥志. "Preparation and Nanomechanical Properties of Aluminum Zinc Oxide Transparent Conducting Thin Films." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/50094713653063757957.
Full textAbstract:
碩士中興大學
材料工程學系所
95
Aluminum zinc oxide transparent conducting thin films possess excellent optical and electrical properties. They can be widely applied to the optoelectronic industry. Thus in this study, the aluminum zinc oxide films were prepared on glass substrates by magnetron sputtering and Sol-gel methods. The microstructures and optical and electrical properties of the films deposited under various deposition parameters were investigated. Besides, their nanomechanical properties and interface adhesion energy were measured by nanoindentation and nanoscratch tests. The aluminum zinc oxide films deposited by sputtering were continuous, dense, and uniform with a columnar structure. Under a low sputtering power and substrate temperature, the obtained films exhibited a roughly spherical particle shape and poor crystallinity. With increasing sputtering power and substrate temperature, the particles became a facet shape with an obvious crystalline structure. The grain size increased with sputtering power and substrate temperature, and consequently the electrical resistivity decreased. The transparency of the aluminum zinc oxide films achieved about 90 %, and the energy band gap was about 3.33 eV. Moreover, the elastic moduli and hardness of the films were about 110 and 8 GPa, respectively. With increasing sputtering power to 200 W, the hardness of the film increased to about 10 GPa. With increasing sputtering power and substrate temperature, the interface adhesion energy measured by the nanoscratch test was improved from 0.49 to 0.86 J/m2. and 0.79 J/m2 , respectively. Moreover, the aluminum zinc oxide films prepared by a Sol-gel method had a smooth surface and over 90 % transparency. The 2 at %aluminum-doped Zinc oxide films had the lowest electrical resistivity of about 5.6 Ω.cm. The elastic modulus and hardness of the aluminum zinc oxide films were measured as 60 and 1.1 GPa , respectively, by the nanoindentation test .
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"Optical properties of metal oxide capped ZnO induced by e-beam irradiation." 2004. http://library.cuhk.edu.hk/record=b5892111.
Full textAbstract:
by Hui Koon-chung = 由電子束照射引起氧化金屬膜覆蓋的氧化鋅之光學特性 / 許冠中.Thesis (M.Phil.)--Chinese University of Hong Kong, 2004.
Includes bibliographical references (leaves 87-89).
Text in English; abstracts in English and Chinese.
by Hui Koon-chung = You dian zi shu zhao she yin qi yang hua jin shu mo fu gai de yang hua xin zhi guang xue te xing / Xu Guanzhong.
ABSTRACT --- p.i
ACKNOWLEDGMENTS --- p.iii
TABLE OF CONTENTS --- p.iv
LIST OF FIGURES --- p.vi
LIST OF TABLES --- p.x
Chapter 1. --- Introduction --- p.1
Chapter 1.1 --- Motivation --- p.1
Chapter 1.2 --- Overview of ZnO
Chapter 1.3 --- Overview of the Thesis
Chapter 2. --- Experimental conditions and procedures --- p.11
Chapter 2.1 --- Samples preparation
Chapter 2.2 --- Optical and electrical Characterizations of ZnO
Chapter 2.2.1 --- Setup of cathodoluminescence (CL) spectroscopy
Chapter 2.2.2 --- Setup of photoluminescence (PL) spectroscopy
Chapter 2.2.3 --- Setup of photoconductivity measurement
Chapter 2.2.4 --- Setup of atomic force microscopy AFM
Chapter 2.2.5 --- X-ray photoelectron spectroscopy (XPS)
Chapter 3. --- Experimental results and data analysis --- p.21
Chapter 3.1 --- The luminescence of ZnO --- p.21
Chapter 3.2 --- Effects of metal capped layer in luminescence --- p.24
Chapter 3.3 --- Optical memory effect of A1 capped ZnO --- p.28
Chapter 3.4 --- The XPS study ofAl capped ZnO --- p.33
Chapter 3.5 --- Optical properties and photoconductivity studies of AlOx-capped ZnO --- p.35
Chapter 3.6 --- Time- and Electron-dose dependent CL of AlOx capped ZnO --- p.41
Chapter 3.7 --- Dependence of band-edge enhancement on Deep Level to band-edge emission ratio --- p.53
Chapter 3.8 --- Temperature-dependent CL of AlOx capped ZnO --- p.56
Chapter 3.9 --- Electrical measurement of luminescence enhanced ZnO --- p.64
Chapter 4. --- Discussion --- p.69
Chapter 4.1 --- General discussion --- p.69
Chapter 4.2 --- The effect of AlOx capping on the optical properties of ZnO --- p.70
Chapter 4.3 --- The action of e-beam irradiation on the enhancement of band-edge emission --- p.73
Chapter 4.4 --- The function of AlOx layer when under electron irradiation --- p.83
Chapter 5. --- Conclusions --- p.85
Reference --- p.87