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1
Whyte, Alex. "Thin film studies of planar transition metal complexes." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7966.
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At present the field of molecular electronics - also known as molecular semiconductors, organic semiconductors, plastic electronics or organic electronics - is dominated by organic materials, both polymeric and molecular, with much less attention being focused on transition metal based complexes despite the advantages they can offer. Such advantages include tuneable frontier orbitals through the ligand/metal interaction and the ability to generate stable paramagnetic species. Devices containing radical materials are particularly interesting in order to examine the interplay between conduction and spin - an effect which is not yet properly understood but can give rise to exotic behaviour. A series of homoleptic, bis-ligand Ni(II) and Cu(II) complexes were prepared using three structurally related phenolic oxime ligands, 2-hydroxy-5-t-octylacetophenone oxime (t-OctsaoH), 2-hydroxy-5-n-propylacetophenone oxime (n-PrsaoH) and 2- hydroxyacetophenone oxime (HsaoH). The complexes were characterised by single-crystal X-ray diffraction, cyclic voltammetry, UV/Vis spectroscopy, field-effect-transistor measurements, DFT/TD-DFT calculations and in the case of the paramagnetic species, EPR and magnetic susceptibility. Variation of the substituent on the ligand from t-octyl to n-propyl to H enabled electronic isolation of the complexes in the crystal structures of M(t-OctsaoH)2, which contrasted with π-stacking interactions observed in the crystal packing of M(n-PrsaoH)2 and of M(HsaoH) (M = Ni, Cu). This was further evidenced by comparing the antiferromagnetic interactions observed in samples of Cu(n-PrsaoH)2 and Cu(HsaoH)2 with the ideal paramagnetic behaviour for Cu(t-OctsaoH)2 down to 1.8 K. Despite isostructural single crystal structures for M(n-PrsaoH)2, thin-film X-ray diffraction and SEM revealed different morphologies depending on the metal and the deposition method employed. However, the complexes of M(n-PrsaoH)2 and M(HsaoH) failed to demonstrate significant charge transport in an FET device despite displaying the ability to form π- stacking structures. A series of planar Ni(II), Cu(II) and Co(II) dibenzotetraaza[14]annulenes (dbtaa) and dinapthotetraaza[14]annulenes (dntaa) were synthesised and studied crystallographically, optically, electrochemically and magnetically. Thin films of each of these complexes have been prepared by vacuum deposition to evaluate the field-effect transistor (FET) performance as well as the morphology and crystallinity of the film formed. Single crystal data revealed that Ni(dbtaa) and Cu(dbtaa) are isomorphous to each other, with Co(dbtaa) displaying a different crystallographic packing. The electrochemistry and UV/Vis absorption studies indicate the materials are redox active and highly coloured, with molar extinction coefficients as large as 80,000 M-1cm-1 in the visible region. The paramagnetic Cu(II) and Co(II) complexes display weak 1-dimensional antiferromagnetic interactions and were fit to the Bonner-Fisher chain model. The data revealed that the Co(II) species possesses much stronger magnetic exchange interactions compared with the Cu(II) complex. Each of the materials formed polycrystalline films when vacuum deposited and all showed ptype field-effect transistor behaviour, with modest charge carrier mobilities in the range of 10-5 to 10-9 cm2 V-1 s-1 . SEM imaging of the substrates indicates that the central metal ion, and its sublimation temperature, has a crucial role in defining the morphology of the resulting film. Structurally related Cu(II) and Ni(II) dithiadiazoletetraaza[14]annulene (dttaa) macrocycles were synthesised and studied in the context of their thin film electrochemical, conducting and morphological properties. Both the Ni(II) and Cu(II) complexes were found to be volatile under reduced pressure, which allowed crystals of both materials to be grown and the single crystal structures solved. Interestingly, the crystal packing of these heterocyclic macrocycles varies depending on whether the central metal ion is Cu(II) or Ni(II), which is in contrast to the analogous dibenzotetrazaannulenes complexes. Soluble Ni(II) analogues containing benzoyl groups on the meso- positions of the macrocycle (dttaaBzOR) were also prepared and contrasted with the insoluble Ni(dttaa) complexes in terms of their solution optical and electrochemical properties. Thin film electrochemical studies of Cu(dttaa) and Ni(dttaa) showed chemically reversible oxidative processes but on scanning to reductive potentials the films disintegrated almost immediately as the bulky counter tetrabutylammonium cation entered the thin film. FET studies undertaken on polycrystalline films of both complexes, using various device configurations and surface treatments, failed to realise any gate effect. Thin film XRD measurements indicate that films of both complexes formed by vacuum deposition are crystalline and contain a mixture of molecular alignments, with molecules aligning “edge on” and “face down” to the substrate. SEM imaging failed to effectively resolve the morphology of the films implying the sizes of the crystallites are small, which may help to explain the lack of FET effect. A series of bis-ligand diimine Ni, Cu and Pd complexes have been synthesised from the ligand 4,5-bis(dodecyloxy)benzene-1,2-diamine (dbdaH2). The same ligand was also used to prepare a series of soluble Cu(II) and Ni(II) tetraaza[14]annulene macrocycles. All the bis-ligand diimine complexes were found to suffer from instability in air due to the ease at which the complexes are oxidised. The Ni complex, Ni(dbda)2, was found to display a NIR transition in the region of 971 to 1024 nm depending on the polarity of the solvent that the molecule is dissolved in. Solution electrochemistry studies of Ni(dbda)2 reaffirmed the facile nature of the first oxidative process, with the HOMO energy calculated at -4 eV by hybrid-DFT. This compound failed to yield semiconducting behaviour in an FET device despite the use of surface treatments aimed at promoting suitable molecular alignment across the conducting channel.
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Roberson, Luke Bennett. "Ultrapurification and deposition of polyaromatic hydrocarbons for field effect transistors." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/30950.
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Roberson, Luke Bennett. "Understanding organic thin film properties for microelectronic organic field-effect transistors and solar cells." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-11072005-111532/.
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Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2006.<br>Mohan Srinivasarao, Committee Member ; David Collard, Committee Member ; Uwe Bunz, Committee Member ; Art Janata, Committee Member ; Marcus Weck, Committee Member ; Laren Tolbert, Committee Chair.
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Tamjidi, Mohammad R. "Characteristics of N-channel accumulation mode thin film polysilicon mosfets. /." Full text open access at:, 1987. http://content.ohsu.edu/u?/etd,132.
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Kwan, Man-chi. "Mobility enhancement for organic thin-film transistors using nitridation method." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37181580.
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Kwan, Man-chi, and 關敏志. "Mobility enhancement for organic thin-film transistors using nitridation method." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37181580.
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Larsson, Oscar. "Polarization characteristics in polyelectrolyte thin film capacitors : Targeting field-effect transistors and sensors." Licentiate thesis, Norrköping : Department of Science and technology, Linköping University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-51547.
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Yurchuk, Ekaterina. "Electrical Characterisation of Ferroelectric Field Effect Transistors based on Ferroelectric HfO2 Thin Films." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-172000.
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Ferroelectric field effect transistor (FeFET) memories based on a new type of ferroelectric material (silicon doped hafnium oxide) were studied within the scope of the present work. Utilisation of silicon doped hafnium oxide (Si:HfO2) thin films instead of conventional perovskite ferroelectrics as a functional layer in FeFETs provides compatibility to the CMOS process as well as improved device scalability. The influence of different process parameters on the properties of Si:HfO2 thin films was analysed in order to gain better insight into the occurrence of ferroelectricity in this system.
A subsequent examination of the potential of this material as well as its possible limitations with the respect to the application in non-volatile memories followed. The Si:HfO2-based ferroelectric transistors that were fully integrated into the state-of-the-art high-k metal gate CMOS technology were studied in this work for the first time. The memory performance of these devices scaled down to 28 nm gate length was investigated. Special attention was paid to the charge trapping phenomenon shown to significantly affect the device behaviour.
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Lee, Jiho. "Impact of process parameter modification on poly(3-hexylthiophene) film morphology and charge transport." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50409.
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Organic electronics based on π-conjugated semi-conductor raises new technology, such as organic film transistors, e-paper, and organic photovoltaic cells that can be implemented cost-effectively on large-area applications. Currently, the device performance is limited by low charge carrier mobility. Poly(3-hexylthiophene) (P3HT) and organic field effect transistors (OFET) is used as a model to investigate morphology of the organic film and corresponding electronic properties. In this thesis, processing parameters such as boiling points and solubility are controlled to impact the micro- and macro-morphology of the film to enhance the charge transport of the device.
Alternative approach to improve ordering of polymer chains and increase in charge transport without post-treatment of P3HT solution is studied. The addition of high boiling good solvent to the relatively low boiling main solvent forms ordered packing of π-conjugated polymers during the deposition process. We show that addition of 1% of dichlorobenzene (DCB) to the chloroform based P3HT solution was sufficient to improve wetting and molecular structures of the film to increase carrier mobility.
Systematic study of solvent-assisted re-annealing technique, which has potential application in OFET encapsulation and fabrication of top-contact OFET, is conducted to improve mobility of OFET, and, to suggest a cost-effective processing condition suitable for industrial application. Three process parameters: boiling point, polarity, and solubility are investigated to further understand the trend of film response to the solvent-assisted technique. We report the high boiling non-polar solvents with relatively high RED values promote highest improvement in molecular packing and formulate crystalline structure of the thin film, which increases the device performance.
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Ternullo, Luigi. "Investigations on thin film polysilicon MOSFETs with Si-Ge ion implanted channels /." Online version of thesis, 1992. http://hdl.handle.net/1850/11166.
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Pang, Lisa Yee San. "Thin film diamond : electronic devices for high temperature, high power and high radiation applications." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313317.
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Martin, Christian Dominik. "Spatially resolved studies of the leakage current behavior of oxide thin-films." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://dx.doi.org/10.18452/16746.
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Im Laufe der Verkleinerungen integrierter Schaltungen ergab sich die Notwendigkeit der alternativen dielektrischen Materialen. Hohe Polarisierbarkeiten in diesen dielektrischen Dünnfilmen treten erst in hoch direktionalen kristallinen Phasen auf. Aufgrund der erschwerten Integrierbarkeit von epitaktischen, einkristallinen Oxidfilmen können nur poly-, beziehungsweise nanokristalle Filme eingesetzt werden. Diese sind jedoch mit hohen Leckströmen behaftet. Weil die Information in einer DRAM-Zelle als Ladung in einem Kondensator gespeichert wird ist der Verlust dieser Ladung durch Leckströme die Ursache für Informationsverluste. Die Frequenz der notwendigen Auffrischungszyklen einer DRAM-Zelle wird direkt durch die Leckströme bestimmt. Voraussetzungen für die Entwicklung neuer dielektrischer Materialien ist das Verständnis der zugrunde liegenden Ladungsträgertransportmechanismen und ein Verständnis der strukturellen Schichteigenschaften, welche zu diesen Leckströmen führen. Conductive atomic force Microscopy ist ein Rastersondenmethode mit der strukturelle Eigenschaften mit lokaler elektrischer Leitfähigkeit korreliert wird. Mit dieser Methode wurde in einer vergleichenden Studie die räumlichen Leckstromverteilungen untersucht. Und es wurde gezeigt, dass es genügt eine nicht geschlossene Zwischenschicht Aluminiumoxid in eine Zirkoniumdioxidschicht zu integrieren um die Leckströme signifikant zu reduzieren während eine ausreichend hohe Kapazität erhalten bleibt. Darüberhinaus wurde ein CAFM modifiziert und benutzt um das Schaltverhalten eines Siliziumnanodrahtschottkybarrierenfeleffektransistor in Abhängigkeit der Spitzenposition zu untersuchen. Es konnte experimentell bestätigt werden das die Schottkybarrieren den Ladungstransport in diesen Bauteilen kontrollieren. Darüber hinaus wurde ein proof-of-concept für eine umprogrammierbaren nichtflüchtigen Speicher, der auf Ladungsakkumulation und der resultierenden Bandverbiegung an den Schottkybarrieren basiert, gezeigt.<br>In the course of the ongoing downscaling of integrated circuits the need for alternative dielectric materials has arisen. The polarizability of these dielectric thin-films is highest in highly directional crystalline phases. Since epitaxial single crystalline oxide films are very difficult to integrate into the complex DRAM fabrication process, poly- or nanocrystalline thin-films must be used. However these films are prone to very high leakage currents. Since the information is stored as charge on a capacitor in the DRAM cell, the loss of this charge through leakage currents is the origin of information loss. The rate of the necessary refresh cycles is directly determined by these leakage currents. A fundamental understanding of the underlying charge carrier transport mechanisms and an understanding of the structural film properties leading to such leakage currents are essential to the development of new, dielectric thin-film materials. Conductive Atomic Force Microscopy (CAFM) is a scanning probe based technique which correlates structural film properties with local electrical conductivity. This method was used to examine the spatial distribution of leakage currents in a comparative study. I was shown that it is sufficient to include an unclosed interlayer of Aluminium oxide into a Zirconium dioxide film to significantly reduce leakage currents while maintaining a sufficiently high capacitance. Moreover, a CAFM was modified and used to examine the switching behavior of a silicon nanowire Schottky barrier field effect transistors in dependence of the probe position. It was proven experimentally that Schottky barriers control the charge carrier transport in these devices. In addition, a proof of concept for a reprogrammable nonvolatile memory device based on charge accumulation and band bending at the Schottky barriers was shown.
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Toporkov, Mykyta. "Growth and Characterization of Wide Bandgap Quaternary BeMgZnO Thin Films and BeMgZnO/ZnO Heterostructures." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4196.
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This thesis reports a comprehensive study of quaternary BeMgZnO alloy and BeMgZnO/ZnO heterostructures for UV-optoelectronics electronic applications. It was shown that by tuning Be and Mg contents in the heterostructures, high carrier densities of two-dimensional electron gas (2DEG) are achievable and makes its use possible for high power RF applications. Additionally, optical bandgaps as high as 5.1 eV were achieved for single crystal wurtzite material which allows the use of the alloy for solar blind optoelectronics (Eg>4.5eV) or intersubband devices.
A systematic experimental and theoretical study of lattice parameters and bandgaps of quaternary BeMgZnO alloy was performed for the whole range of compositions. Composition independent bowing parameters were determined which allows accurate predictions of experimentally measured values.
The BeMgZnO thin films were grown by plasma assisted molecular beam epitaxy (P-MBE) in a wide range of compositions. The optimization of the growth conditions and its effects on the material properties were explored. The surface morphology and electrical characteristics of the films grown on (0001) sapphire were found to critically depend on the metal-to-oxygen ratio. Samples grown under slightly oxygen-rich conditions exhibited the lowest RMS surface roughness (as low as 0.5 nm). Additionally, the films grown under oxygen-rich conditions were semi-insulating (>105 Ω∙cm), while the films grown under metal-rich conditions were semiconducting (~102 Ω∙cm). Additionally, with increasing bandgap Stokes shift increases, reaching ~0.5 eV for the films with 4.6 eV absorption edge suggests the presence of band tail states introduced by potential fluctuations and alloying.
From spectrally resolved PL transients, BeMgZnO films grown on a GaN/sapphire template having higher Mg/Be content ratio exhibit smaller localization depth and brighter photoluminescence at low temperatures. The optimum content ratio for better room temperature optical performance was found to be ~2.5.
The BeMgZnO material system and heterostructures are promising candidates for the device fabrication. 2DEG densities of MgZnO/ZnO heterostructures were shown to improve significantly (above 1013 cm-2) by adding even a small amount of Be (1-5%). As an essential step toward device fabrication, reliable ohmic contacts to ZnO were established with remarkably low specific contact resistivities below 10-6 Ohm-cm2 for films with 1018 cm-3 carrier density.
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Lebon, Florian. "Nano-composants à base de films minces organiques électrogreffés : Fabrication, caractérisation, étude du transport électronique et intégration." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS286/document.
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Le principal objectif de cette thèse est de montrer le potentiel pour l’électronique organique de films moléculaires minces liés de façon covalente au substrat et déposés par greffage électro- chimique. Ces couches organiques de 5 à 100 nm d’épaisseur visent à proposer une alternative aux films minces organiques d’épaisseur supérieure à 100 nm et aux couches mono-moléculaires autoassemblées d’épaisseur comprise entre 1 et 5 nm.Ce travail a d’abord permis d’établir les conditions optimales de greffage de trois différents sels de diazonium : un dérivé de la tris-bipyridine fer (II), un sel de diazonium comportant une longue chaîne fluorée et un autre comportant une fonction thiol. En particulier, un contrôle fin de l’épaisseur des films est démontré sur des électrodes patternées micrométriques adaptées à la réalisation de dispositifs.L’électrogreffage de doubles couches est ensuite étudié. Il consiste à utiliser une électrode electrogreffée par des molécule électroactives, ici le dérivé de la tris-bipyridine fer (II), comme électrode de travail pour l’électrogreffage d’un second sel de diazonium. Cette technique permet de former des couches organiques d’épaisseur contrôlée par la première couche et présentant des fonctions terminales contrôlées par le choix du second composé (ici, fonctions thiols ou chaînes fluorées). L’intérêt de ces couches fonctionnelles est ensuite évalué dans des jonctions verticales métal-molécules-métal utilisant différents types d’électrodes supérieures : des électrodes imprimées à partir d’une solution de nanoparticules d’or, suivant un procédé élaboré dans cette thèse, et des électrodes fabriquées à partir de métaux évaporés sous vide. Enfin, des transistors à base de MoS2 utilisant 30 nm de ces couches greffées comme diélectrique de grille sont fabriqués et étudiés. Leurs performances (mobilité électronique de 46 cm2.(V.s)-1, rapport ION/IOFF de 9.107, etc.) confirment la qualité de ces isolants organiques électrogreffés. La méthode s’avère ainsi efficace et versatile pour la préparation de couches organiques robustes d’épaisseur contrôlée et aux propriétés de surface ajustables<br>The main objective of this PhD thesis is to show the potential for organic electronics of molecular thin films covalently bounded and formed by electrochemical grafting. These 5 to 100 nm thick layers aim to propose an alternative to organic thin films of thickness above 100 nm and to self-assembled monolayers of thickness between 1 and 5 nm.This work first establishes the optimal electrografting conditions of three diazonium salts : a derivative from the tris-bipyridine iron (II), a diazonium salt with a long fluorinated chain and another with a thiol function). In particular, a fine tuning of the thickness of the resulting layers is demonstrated on micrometric patterned electrodes.Double layer electrografting is then studied. It consists in using an electrode electrografted with electroactive molecules, here the tris-bipyridine iron (II) derivative, as a working electrode for the electrografting of a second diazonium salt. This technique allows the formation of organic double-layers of thickness controlled by the first layer and presenting terminal functions controlled by the choice of the second compound (here, thiol functions or fluorinated chains).The potential of these layers is then evaluated in vertical metal-molecules-metal junctions using various top electrodes : electrodes printed from an aqueous gold nanoparticle ink through a method developed in this thesis, and electrodes made by metal evaporation in vacuum. To conclude, field-effect transistors based on MoS2 using these electrografted thin layers as gate-dielectric are fabricated and studied. Their performances (electronic mobility of 46 cm2.(V.s)-1, ION/IOFF ratio of 9.107,etc.) confirm the quality of these organic electrografted insulators. The method is thus efficient and versatile for the preparation of robust organic layers with adjustable surface properties and thickness
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Benachir, Mohcine. "Simulation numérique et modélisation des transistors MOS sur silicium sur isolant à inversion volumique." Grenoble INPG, 1989. http://www.theses.fr/1989INPG0090.
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Dans la premiere partie de la these, nous presentons un nouveau mode de fonctionnement des transistors mos sur silicium sur isolant, qui consiste dans l'inversion forte et totale du film de silicium. Nous presentons ensuite les avantages induits par ce nouveau mode de fonctionnement. Nous montrons aussi qu'il est possible d'etablir, dans les deux cas extremes de transistors a film de silicium respectivement tres mince et tres epais, des modeles analytiques simples qui decrivent adequatement le fonctionnement electrique des tmos a volume inverse (tmos-vi) en regime ohmique. La deuxieme partie est consacree a la presentation des diverses techniques numeriques et equations physiques que nous avons retenues pour la realisation du simulateur electrique bidimensionnel des structures tmos-ssi: isis ii. L'objet de la troisieme partie est d'illustrer les possibilites d'etudes par la simulation electrique des dispositifs ssi, offertes par isis ii
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Ullah, Syed Shihab. "Solution Processing Electronics Using Si6 H12 Inks: Poly-Si TFTs and Co-Si MOS Capacitors." Thesis, North Dakota State University, 2011. https://hdl.handle.net/10365/28902.
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The development of new materials and processes for electronic devices has been driven by the integrated circuit (IC) industry since the dawn of the computer era. After several decades of '"Moore's Law"-type innovation, future miniaturization may be slowed down by materials and processing limitations. By way of comparison, the nascent field of flexible electronics is not driven by the smallest possible circuit dimension, but instead by cost and form-factor where features typical of 1970s CMOS (i.e., channel length - IO ?m) will enable flexible electronic technologies such as RFID, e-paper, photovoltaics and health monitoring devices. In this thesis. cyclohexasilane is proposed and used as a key reagent in solution processing of poly-Si and Co-Si thin films with the former used as the active layer in thin film transistors (TFTs) and the latter as the gate metal in metal-oxide-semiconductor (MOS) capacitors. A work function of 4.356 eV was determined for the Co-Si thin films via capacitance-voltage (C-Y) characterization which differs slightly from that extracted from ultraviolet photoemission spectroscopy (UPS) data (i.e., 4.8 eV). Simulation showed the difference between the C-V and UPS-derived data may be attributed to the existence of 8.3 x 10 (exponent 10) cm-2 interface charge density in the oxide-semiconductor junction. Poly-Si TFTs prepared using Si6 H12-based inks maintained the following electrical attributes: field effect mobility of 0.1 cm2V-1s-1; threshold voltage of 66 V; and, an on/off ratio of 1630. A BSIM3 version 3 NFET model was modified through global parametric extraction procedure to match the transfer characteristics of the fabricated poly-Si TFT. It is anticipated that this model can be utilized for future design simulation for solution-processed poly-Si circuits.
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Ryu, Hyeyeon. "Integrated Circuits Based on Individual Single-Walled Carbon Nanotube Field-Effect Transistors." Doctoral thesis, Universitätsbibliothek Chemnitz, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-98220.
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This thesis investigates the fabrication and integration of nanoscale field-effect transistors based on individual semiconducting carbon nanotubes. Such devices hold great potential for integrated circuits with large integration densities that can be manufactured on glass or flexible plastic substrates. A process to fabricate arrays of individually addressable carbon-nanotube transistors has been developed, and the electrical characteristics of a large number of transistors has been measured and analyzed. A low-temperature-processed gate dielectric with a thickness of about 6 nm has been developed that allows the transistors and circuits to operate with voltages of about 1.5 V. The transistors show excellent electrical properties, including a large transconductance (up to 10 µS), a large On/Off ratio (>10^4), a steep subthreshold swing (65 mV/decade), and negligible leakage currents (~10^-13 A). For the realization of unipolar logic circuits, monolithically integrated load resistors based on high-resistance metallic carbon nanotubes or vacuum-evaporated carbon films have been developed and analyzed by four-probe and transmission line measurements. A variety of combinational logic circuits, such as inverters, NAND gates and NOR gates, as well as a sequential logic circuit based on carbon-nanotube transistors and monolithically integrated resistors have been fabricated on glass substrates and their static and dynamic characteristics have been measured. Optimized inverters operate with frequencies as high as 2 MHz and switching delay time constants as short as 12 ns<br>Thema dieser Arbeit ist die Herstellung und Integration von Feldeffekt-Transistoren auf der Grundlage einzelner halbleitender Kohlenstoffnanoröhren. Solche Bauelemente sind zum Beispiel für die Realisierung integrierter Schaltungen mit hoher Integrationsdichte auf Glassubstraten oder auf flexiblen Kunststofffolien von Interesse. Zunächst wurde ein Herstellungsverfahren für die Anfertigung einer großen Anzahl solcher Transistoren auf Glas- oder Kunststoffsubstraten entwickelt, und deren elektrische Eigenschaften wurden gemessen und ausgewertet. Das Gate-Dielektrikum dieser Transistoren hat eine Schichtdicke von etwa 6 nm, so das die Versorgungsspannungen bei etwa 1.5 V liegen. Die Transistoren haben sehr gute elektrische Parameter, z.B. einen großen Durchgangsleitwert (bis zu 10 µS), ein großes Modulationsverhältnis (>10^4), einen steilen Unterschwellanstieg (65 mV/Dekade) und vernachlässigbar kleine Leckströme (~10^-13 A). Für die Realisierung unipolarer Logikschaltungen wurden monolithisch integrierte Lastwiderstände auf der Grundlage metallischer Kohlenstoffnanoröhren mit großem Widerstand oder mittels Vakuumabscheidung erzeugter Kohlenstoffschichten entwickelt und u. a. mittels Vierpunkt- und Transferlängen-Messungen analysiert. Eine Reihe kombinatorischer Schaltungen, z.B. Inverter, NAND-Gatter und NOR-Gatter, sowie eine sequentielle Logikschaltung wurden auf Glassubstraten hergestellt, und deren statische und dynamische Parameter wurden gemessen. Optimierte Inverter arbeiten bei Frequenzen von bis zu 2 MHz und haben Signalverzögerungen von lediglich 12 ns
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Park, June Hyoung. "Charge transport in organic multi-layer devices under electric and optical fields." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1182273300.
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Deutsch, Denny. "Nanostrukturierte Fullerenschichten für organische Bauelemente." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-23699.
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Die vorliegende Arbeit behandelt die Herstellung geordneter C60-Schichten, ihre elektrochemische Nanostrukturierung in wässrigen Lösungen und ionischen Flüssigkeiten und den Einsatz geordneter und nanostrukturierter Fullerenschichten in organischen Dünnschichttransistoren.
Geordnete C60-Schichten wurden durch thermische Verdampfung im Hochvakuum hergestellt. Als Substratmaterial wurden HOPG (Graphit), Glimmer und einkristallines Silizium verwendet. Die größten einkristallinen Bereiche werden auf HOPG-Substraten erhalten. Die laterale Ausdehnung der C60-Kristallite parallel zu den Graphitstufen kann bis zu 50 µm erreichen, orthogonal zu den Stufen ist das Wachstum durch die Graphitstufen begrenzt.
Die elektrochemische Reduktion von C60 -Schichten in wässriger Lösung ist elektrochemisch irreversibel. Die geflossene Ladung beträgt ein Vielfaches der theoretisch möglichen Menge. Durch die Reduktion tritt eine Nanostrukturierung der Schichtoberfläche ein, die Größe der gebildeten Cluster beträgt 20 nm bis 50 nm. Fullerenpolymere und hydriertes C60 sind die chemischen Hauptprodukte der elektrochemischen Nanostrukturierung in wässriger Lösung.
Die Reduktion von Fullerenschichten in ionischen Flüssigkeiten ist aufgrund der geschlossenen Schichtoberfläche und des starken Potentialabfalls in der Fullerenschicht zunächst kinetisch gehemmt und setzt erst bei negativeren Potentialen im Bereich der Reduktion zum C60-Dianion ein. Die Reduktion der Fullerenschichten ist elektrochemisch irreversibel, zum Teil aber chemisch reversibel.
Es konnte erstmals der Einsatz nanostrukturierter C60 -Schichten als aktives Halbleitermaterial in Feldeffekt-Transistoren gezeigt werden. Für die Verwendung nanostrukturierter Fullerenschichten in Feldeffekt-Transistoren wurde 11-(3-Thienyl-)undecyl-trichlorosilan als Haftvermittler eingesetzt.
Die gezeigten Ergebnisse von C60 -Transistoren mit hoher Ladungsträgerbeweglichkeit und der erfolgreichen Verwendung nanostrukturierter Fullerenschichten in Transistorstrukturen zeigen die Möglichkeiten des C60 als aktives Halbleitermaterial auf.
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Deutsch, Denny. "Nanostrukturierte Fullerenschichten für organische Bauelemente." Doctoral thesis, Technische Universität Dresden, 2007. https://tud.qucosa.de/id/qucosa%3A25079.
Full textAbstract:
Die vorliegende Arbeit behandelt die Herstellung geordneter C60-Schichten, ihre elektrochemische Nanostrukturierung in wässrigen Lösungen und ionischen Flüssigkeiten und den Einsatz geordneter und nanostrukturierter Fullerenschichten in organischen Dünnschichttransistoren.
Geordnete C60-Schichten wurden durch thermische Verdampfung im Hochvakuum hergestellt. Als Substratmaterial wurden HOPG (Graphit), Glimmer und einkristallines Silizium verwendet. Die größten einkristallinen Bereiche werden auf HOPG-Substraten erhalten. Die laterale Ausdehnung der C60-Kristallite parallel zu den Graphitstufen kann bis zu 50 µm erreichen, orthogonal zu den Stufen ist das Wachstum durch die Graphitstufen begrenzt.
Die elektrochemische Reduktion von C60 -Schichten in wässriger Lösung ist elektrochemisch irreversibel. Die geflossene Ladung beträgt ein Vielfaches der theoretisch möglichen Menge. Durch die Reduktion tritt eine Nanostrukturierung der Schichtoberfläche ein, die Größe der gebildeten Cluster beträgt 20 nm bis 50 nm. Fullerenpolymere und hydriertes C60 sind die chemischen Hauptprodukte der elektrochemischen Nanostrukturierung in wässriger Lösung.
Die Reduktion von Fullerenschichten in ionischen Flüssigkeiten ist aufgrund der geschlossenen Schichtoberfläche und des starken Potentialabfalls in der Fullerenschicht zunächst kinetisch gehemmt und setzt erst bei negativeren Potentialen im Bereich der Reduktion zum C60-Dianion ein. Die Reduktion der Fullerenschichten ist elektrochemisch irreversibel, zum Teil aber chemisch reversibel.
Es konnte erstmals der Einsatz nanostrukturierter C60 -Schichten als aktives Halbleitermaterial in Feldeffekt-Transistoren gezeigt werden. Für die Verwendung nanostrukturierter Fullerenschichten in Feldeffekt-Transistoren wurde 11-(3-Thienyl-)undecyl-trichlorosilan als Haftvermittler eingesetzt.
Die gezeigten Ergebnisse von C60 -Transistoren mit hoher Ladungsträgerbeweglichkeit und der erfolgreichen Verwendung nanostrukturierter Fullerenschichten in Transistorstrukturen zeigen die Möglichkeiten des C60 als aktives Halbleitermaterial auf.
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Maciel, Alexandre de Castro. "Fabricação e estudo das propriedades de transporte de transistores de filmes finos orgânicos." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-18122012-114317/.
Full textAbstract:
A eletrônica digital desempenha papel essencial no desenvolvimento e manutenção dos padrões de vida em prática hoje no mundo. A peça fundamental para a criação desta era tecnológica é sem dúvidas o transistor. Com o advento de novos materiais, a busca por transistores que oferecem novas oportunidades de processamento e aplicação permitiu que uma nova área fosse criada: a eletrônica orgânica. Transistores de efeito de campo baseados em filmes finos de materiais orgânicos têm recebido grande atenção nas últimas décadas. Apresentamos um estudo experimental e teórico de transistores de efeito de campo a base de filmes finos orgânicos. Foram caracterizados transistores usando um derivado do pentaceno (TMTES-pentaceno) como camada ativa em um dispositivo feito sobre Si/SiO2. Mostramos que a inclusão do semicondutor orgânico em uma matriz polimérica isolante ajuda a manter a estabilidade termo mecânica do dispositivo. Foi desenvolvido um modelo que levasse em conta as resistências parasíticas para explicar o comportamento do transistor em função da temperatura. Também foram construídos e caracterizados transistores usando rr-P3HT como semicondutor e PMMA como isolantes. Apresentamos transistores do tipo Top-Gate e Bottom-Gate com mobilidade máxima de 7 x 10-3 cm2/V.s. Valores de razão ON/OFF de ~ 900 foram encontrados nos transistores otimizados. O comportamento dos transistores é analisado em função da temperatura e os modelos de aproximação de canal gradual e de Vissenberg-Matters foram aplicados para extração dos parâmetros de interesse. Por fim, apresentamos um modelo de corrente de canal baseado na resolução 2D numérica da equação de Poisson usando as idéias de Vissenberg-Matters para a concentração de cargas em função do potencial local. O modelo, embora ainda nos primeiros estágios de desenvolvimento, prevê a saturação da corrente nas curvas de saída simuladas sem limitações de regime de validade.<br>Digital electronics plays an essential role in the development and maintenance of living standards into practice in the world today. The cornerstone for the creation of this technological age is undoubtedly the transistor. With the advent of new materials, the search for transistors that offer new opportunities in processing and application allowed a new area to be created: the organic electronics. Field effect transistors based on organic thin films have received great attention in recent decades. We report an experimental and theoretical study of field effect transistors based on organic thin films. We characterized transistors manufactured using a derivative of pentacene (TMTES-pentacene) as the active layer in a device and using Si/SiO2 as gate and insulator. We show that the inclusion of the organic semiconductor in an insulating polymeric matrix helps to maintain the termo-mechanical stability of the device. A model was developed that take into account the parasitic resistances and to explain the behavior of the transistor as a function of temperature. We also present the manufacturing and characterization process of transistors using rr-P3HT as semiconductor and PMMA as insulator. We report Top-Gate and Bottom-Gate transistors with maximum mobility of 7 x 10-3 cm2/V.s. The maximun ON/OFF ratio of ~ 900 was found for the optimized transistors. The behavior of the transistors was analyzed as a function of temperature and both gradual channel approximation and Vissenberg-Matters models were applied for extracting the parameters. Finally, we present a channel current model based on the resolution of 2D numerical Poisson equation using the ideas of Vissenberg-Matters to the calculate the concentration of charges due to the local potential. The model, although still in the early stages of development, predicts the saturation current at output simulated curves with no limitation of regime validity.
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Lindner, Thomas. "Organische Feldeffekt-Transistoren: Modellierung und Simulation." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1116323078792-49660.
Full textAbstract:
Die vorliegende Arbeit befasst sich mit der Simulation und Modellierung organischer Feldeffekt-Transistoren (OFETs). Mittels numerischer Simulationen wurden detaillierte Untersuchungen zu mehreren Problemstellungen durchgeführt. So wurde der Einfluss einer exponentiellen Verteilung von Trapzuständen, entsprechend dem sogenannten a-Si- oder TFT-Modell, auf die Transistorkennlinien untersucht. Dieses Modell dient der Beschreibung von Dünnschicht-Transistoren mit amorphen Silizium als aktiver Schicht und wird teils auch für organische Transistoren als zutreffend angesehen. Dieser Sachverhalt wird jedoch erstmals in dieser Arbeit detailliert untersucht und simulierte Kennlinien mit gemessenen Kennlinien von OFETs verglichen. Insbesondere aufgrund der Dominanz von Hysterese-Effekten in experimentellen Kennlinien ist jedoch eine endgültige Aussage über die Gültigkeit des a-Si-Modells schwierig. Neben dem a-Si-Modell werden auch noch andere Modelle diskutiert, z.B. Hopping-Transport zwischen exponentiell verteilten lokalisierten Zuständen (Vissenberg, Matters). Diese Modelle liefern, abhängig von den zu wählenden Modellparametern, zum Teil ähnliche Abhängigkeiten. Möglicherweise müssen die zu wählenden Modellparameter selbst separat gemessen werden, um eindeutige Schlussfolgerungen über den zugrundeliegenden Transportmechanismus ziehen zu können. Unerwünschte Hysterese-Effekte treten dabei sowohl in Transistorkennlinien als auch in Kapazitäts-Spannungs- (CV-) Kennlinien organischer MOS-Kondensatoren auf. Diese Effekte sind bisher weder hinreichend experimentell charakterisiert noch von ihren Ursachen her verstanden. In der Literatur findet man Annahmen, dass die Umladung von Trapzuständen oder bewegliche Ionen ursächlich sein könnten. In einer umfangreichen Studie wurde daher der Einfluß von Trapzuständen auf quasistatische CV-Kennlinien organischer MOS-Kondensatoren untersucht und daraus resultierende Hysterese-Formen vorgestellt. Aus den Ergebnissen läßt sich schlussfolgern, dass allein die Umladung von Trapzuständen nicht Ursache für die experimentell beobachteten Hysteresen in organischen Bauelementen sein kann. Eine mögliche Erklärung für diese Hysterese-Effekte wird vorgeschlagen und diskutiert. In einem weiteren Teil der Arbeit wird im Detail die Arbeitsweise des source-gated Dünnschicht-Transistors (SGT) aufgezeigt, ein Transistortyp, welcher erst kürzlich in der Literatur eingeführt wurde. Dies geschieht am Beispiel eines Transistors auf der Basis von a-Si als aktiver Schicht, die Ergebnisse lassen sich jedoch analog auch auf organische Transistoren übertragen. Es wird geschlussfolgert, dass der SGT ein gewöhnlich betriebener Dünnschicht-Transistor ist, limitiert durch das Sourcegebiet mit großem Widerstand. Die detaillierte Untersuchung des SGT führt somit auf eine Beschreibung, die im Gegensatz zur ursprünglich verbal diskutierten Arbeitsweise steht. Ambipolare organische Feldeffekt-Transistoren sind ein weiterer Gegenstand der Arbeit. Bei der Beschreibung ambipolarer Transistoren vernachlässigen bisherige Modelle sowohl die Kontakteigenschaften als auch die Rekombination von Ladungsträgern. Beides wird hingegen in den vorgestellten numerischen Simulationen erstmalig berücksichtigt. Anhand eines Einschicht-Modellsystems wurde die grundlegende Arbeitsweise von ambipolaren (double-injection) OFETs untersucht. Es wird der entscheidende Einfluß der Kontakte sowie die Abhängigkeit gegenüber Variationen von Materialparametern geklärt. Sowohl der Kontakteinfluß als auch Rekombination sind entscheidend für die Arbeitsweise. Zusätzlich werden Möglichkeiten und Einschränkungen für die Datenanalyse mittels einfacher analytischer Ausdrücke aufgezeigt. Es zeigte sich, dass diese nicht immer zur Auswertung von Kennlinien herangezogen werden dürfen. Weiterhin werden erste Simulationsergebnisse eines ambipolaren organischen Heterostruktur-TFTs mit experimentellen Daten verglichen.
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Lindner, Thomas. "Organische Feldeffekt-Transistoren: Modellierung und Simulation." Doctoral thesis, Technische Universität Dresden, 2004. https://tud.qucosa.de/id/qucosa%3A24492.
Full textAbstract:
Die vorliegende Arbeit befasst sich mit der Simulation und Modellierung organischer Feldeffekt-Transistoren (OFETs). Mittels numerischer Simulationen wurden detaillierte Untersuchungen zu mehreren Problemstellungen durchgeführt. So wurde der Einfluss einer exponentiellen Verteilung von Trapzuständen, entsprechend dem sogenannten a-Si- oder TFT-Modell, auf die Transistorkennlinien untersucht. Dieses Modell dient der Beschreibung von Dünnschicht-Transistoren mit amorphen Silizium als aktiver Schicht und wird teils auch für organische Transistoren als zutreffend angesehen. Dieser Sachverhalt wird jedoch erstmals in dieser Arbeit detailliert untersucht und simulierte Kennlinien mit gemessenen Kennlinien von OFETs verglichen. Insbesondere aufgrund der Dominanz von Hysterese-Effekten in experimentellen Kennlinien ist jedoch eine endgültige Aussage über die Gültigkeit des a-Si-Modells schwierig. Neben dem a-Si-Modell werden auch noch andere Modelle diskutiert, z.B. Hopping-Transport zwischen exponentiell verteilten lokalisierten Zuständen (Vissenberg, Matters). Diese Modelle liefern, abhängig von den zu wählenden Modellparametern, zum Teil ähnliche Abhängigkeiten. Möglicherweise müssen die zu wählenden Modellparameter selbst separat gemessen werden, um eindeutige Schlussfolgerungen über den zugrundeliegenden Transportmechanismus ziehen zu können. Unerwünschte Hysterese-Effekte treten dabei sowohl in Transistorkennlinien als auch in Kapazitäts-Spannungs- (CV-) Kennlinien organischer MOS-Kondensatoren auf. Diese Effekte sind bisher weder hinreichend experimentell charakterisiert noch von ihren Ursachen her verstanden. In der Literatur findet man Annahmen, dass die Umladung von Trapzuständen oder bewegliche Ionen ursächlich sein könnten. In einer umfangreichen Studie wurde daher der Einfluß von Trapzuständen auf quasistatische CV-Kennlinien organischer MOS-Kondensatoren untersucht und daraus resultierende Hysterese-Formen vorgestellt. Aus den Ergebnissen läßt sich schlussfolgern, dass allein die Umladung von Trapzuständen nicht Ursache für die experimentell beobachteten Hysteresen in organischen Bauelementen sein kann. Eine mögliche Erklärung für diese Hysterese-Effekte wird vorgeschlagen und diskutiert. In einem weiteren Teil der Arbeit wird im Detail die Arbeitsweise des source-gated Dünnschicht-Transistors (SGT) aufgezeigt, ein Transistortyp, welcher erst kürzlich in der Literatur eingeführt wurde. Dies geschieht am Beispiel eines Transistors auf der Basis von a-Si als aktiver Schicht, die Ergebnisse lassen sich jedoch analog auch auf organische Transistoren übertragen. Es wird geschlussfolgert, dass der SGT ein gewöhnlich betriebener Dünnschicht-Transistor ist, limitiert durch das Sourcegebiet mit großem Widerstand. Die detaillierte Untersuchung des SGT führt somit auf eine Beschreibung, die im Gegensatz zur ursprünglich verbal diskutierten Arbeitsweise steht. Ambipolare organische Feldeffekt-Transistoren sind ein weiterer Gegenstand der Arbeit. Bei der Beschreibung ambipolarer Transistoren vernachlässigen bisherige Modelle sowohl die Kontakteigenschaften als auch die Rekombination von Ladungsträgern. Beides wird hingegen in den vorgestellten numerischen Simulationen erstmalig berücksichtigt. Anhand eines Einschicht-Modellsystems wurde die grundlegende Arbeitsweise von ambipolaren (double-injection) OFETs untersucht. Es wird der entscheidende Einfluß der Kontakte sowie die Abhängigkeit gegenüber Variationen von Materialparametern geklärt. Sowohl der Kontakteinfluß als auch Rekombination sind entscheidend für die Arbeitsweise. Zusätzlich werden Möglichkeiten und Einschränkungen für die Datenanalyse mittels einfacher analytischer Ausdrücke aufgezeigt. Es zeigte sich, dass diese nicht immer zur Auswertung von Kennlinien herangezogen werden dürfen. Weiterhin werden erste Simulationsergebnisse eines ambipolaren organischen Heterostruktur-TFTs mit experimentellen Daten verglichen.
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Lei, Yanlian. "Morphology and microstructure control of conjugated polymer thin films for high performance field-effect transistors." HKBU Institutional Repository, 2016. https://repository.hkbu.edu.hk/etd_oa/321.
Full textAbstract:
Charge transport in semiconductor channels of organic field-effect transistors (FETs) depends largely on the molecular ordering of organic semiconductor molecules. This is particularly demanding for polymer-based FETs, where channel semiconductors are non-molecular in nature, and generally form semiconductor films of low crystallinity. As a result, great theoretical and practical interests have been directed towards facile solution processes that can transform a low molecular weight (MW) and low mobility conjugated polymer into a high crystalline order and high-mobility semiconductor. This research focuses on developing effective strategies for achieving high mobility as well as other desirable FET properties through properly controlling the morphology and molecular ordering of conjugated polymer channel layers. The relationships between morphologic/microstructural properties of the polymer semiconductor films and charge transport characteristics in the films are systematically investigated and elucidated. The purpose of this work is to achieve high performance solution-processed polymer FETs with high mobility, excellent ambient stability, and performance uniformity that display practical significance for application in next-generation electronics. In the first part of this thesis, functionalization of the gate dielectric surface by grafting highly ordered and dense coverage of hybrid silane self-assembled monolayers (SAMs) is discussed. A two-step solution-processed method using a combination of trichlorooctadecylsilane (OTS-18) and trichlorooctylsilane (OTS-8) has been developed to create high-performance hybrid dual-silane SAM on the surface of silicon dioxide (SiO2), thus enabling the achievement of both high field-effect mobility and current on/off ratio, together with other desirable FET properties. The hybrid SAM approach is also adopted for attaining high performing polymer FETs using a different SAM agent combination of phenyltrichlorosilane (PTS) and OTS-18. With the progress in functionalizing the surface of gate dielectric insulator by two-step grafting SAMs, the advancement in enhancing the crystalline structural order of the polymer channel layer is highlighted. This was realized by the incorporation of polar insulator of polyacrylonitrile (PAN) into the polymer semiconductor solution at appropriate loadings, enabling the formation of excellent semiconductor films with high crystalline order. PAN serves as an efficient mediating medium for the crystallization of polymer semiconductor, leading to the creation of large crystalline domains within the PAN matrix. A 1̃0-nm thick semiconductor layer with richer semiconductor crystalline domains is constructed near the vicinity of the gate dielectric surface, facilitating efficient charge conduction in the channel semiconductor. Enhancements in field-effect mobility by as much as about one order in magnitude and current on/off ratio of two to three orders in magnitude have been realized in polymer FETs. PAN incorporation also dramatically enhances the stability and processability of semiconductor solutions, enabling rapid fabrication of channel semiconductors in polymer FETs via common graphic art printing techniques such as inkjet printing for practical adoption. Another unique facile solution process which transforms a lower-MW and low-mobility conjugated polymer, e.g., diketopyrrolopyrrole-dithienylthieno[3,2-b] thiophene (DPP-DTT), into a high crystalline order and high-mobility nanowire network for high performance polymer FETs has been also developed in this work. This approach involves solution fabrication of a channel semiconductor film using a lower MW DPP-DTT/polystyrene blend system. With the help of cooperative shifting motions of polystyrene chain segments, an interpenetrating nanowire semiconductor network is readily self-assembled and crystallized out in the polystyrene matrix, and thereby providing significantly enhanced mobility (over 8 cm2 V-1 s-1) and current on/off ratio (107). Finally, the concept of generating polymer nanowire network in the effective photoactive channel is extended for the development of highly sensitive near-infrared (NIR) organic phototransistors (OPTs). The NIR-OPTs based on DPP-DTT nanowire network exhibit high responsivity of 2̃46 A W-1 under an NIR illumination source with the wavelength of 850 nm at a low intensity of ̃0.1 mW cm-2. This value is over one order in magnitude higher than that of the structurally identical planar DPP-DTT thin film based OPTs. The high performance of the nanowire network-based phototransistors is attributed to the excellent hole transport ability, reduced density of the structural defects in the polymer nanowire network, and improved contact at the channel layer/electrode interfaces. The high sensitivity and low cost solution-fabrication process render this OPT technology appealing and practically viable for application in large area NIR sensors.
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Niebel, Claude, Yeongin Kim, Christian Ruzié, et al. "Thienoacene dimers based on the thieno[3,2-b] thiophene moiety: synthesis, characterization and electronic properties." Royal Society of Chemistry, 2015. https://tud.qucosa.de/id/qucosa%3A36261.
Full textAbstract:
Two thienoacene dimers based on the thieno[3,2-b]thiophene moiety were efficiently synthesized, characterized and evaluated as active hole-transporting layers in organic thin-film field-effect transistors. Both compounds behaved as active p-channel organic semi-conductors showing averaged hole mobility of up to 1.33 cm² V⁻¹ s⁻¹.
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Liu, Wen. "Design, Characterization and Analysis of Electrostatic Discharge (ESD) Protection Solutions in Emerging and Modern Technologies." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5404.
Full textAbstract:
Electrostatic Discharge (ESD) is a significant hazard to electronic components and systems. Based on a specific processing technology, a given circuit application requires a customized ESD consideration that includes the devices' operating voltage, leakage current, breakdown constraints, and footprint. As new technology nodes mature every 3-5 years, design of effective ESD protection solutions has become more and more challenging due to the narrowed design window, elevated electric field and current density, as well as new failure mechanisms that are not well understood. The endeavor of this research is to develop novel, effective and robust ESD protection solutions for both emerging technologies and modern complementary metal–oxide–semiconductor (CMOS) technologies. The Si nanowire field-effect transistors are projected by the International Technology Roadmap for Semiconductors as promising next-generation CMOS devices due to their superior DC and RF performances, as well as ease of fabrication in existing Silicon processing. Aiming at proposing ESD protection solutions for nanowire based circuits, the dimension parameters, fabrication process, and layout dependency of such devices under Human Body Mode (HBM) ESD stresses are studied experimentally in company with failure analysis revealing the failure mechanism induced by ESD. The findings, including design methodologies, failure mechanism, and technology comparisons should provide practical knowhow of the development of ESD protection schemes for the nanowire based integrated circuits. Organic thin-film transistors (OTFTs) are the basic elements for the emerging flexible, printable, large-area, and low-cost organic electronic circuits. Although there are plentiful studies focusing on the DC stress induced reliability degradation, the operation mechanism of OTFTs subject to ESD is not yet available in the literature and are urgently needed before the organic technology can be pushed into consumer market. In this work, the ESD operation mechanism of OTFT depending on gate biasing condition and dimension parameters are investigated by extensive characterization and thorough evaluation. The device degradation evolution and failure mechanism under ESD are also investigated by specially designed experiments. In addition to the exploration of ESD protection solutions in emerging technologies, efforts have also been placed in the design and analysis of a major ESD protection device, diode-triggered-silicon-controlled-rectifier (DTSCR), in modern CMOS technology (90nm bulk). On the one hand, a new type DTSCR having bi-directional conduction capability, optimized design window, high HBM robustness and low parasitic capacitance are developed utilizing the combination of a bi-directional silicon-controlled-rectifier and bi-directional diode strings. On the other hand, the HBM and Charged Device Mode (CDM) ESD robustness of DTSCRs using four typical layout topologies are compared and analyzed in terms of trigger voltage, holding voltage, failure current density, turn-on time, and overshoot voltage. The advantages and drawbacks of each layout are summarized and those offering the best overall performance are suggested at the end.<br>Ph.D.<br>Doctorate<br>Electrical Engineering and Computer Science<br>Engineering and Computer Science<br>Electrical Engineering
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Liu, Zhihong. "A study of thermally nitrided silicon dioxide thin films for metal-oxide-silicon VLSI techology /." [Hong Kong : University of Hong Kong], 1990. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12718488.
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McCarthy, John M. "The microstructural effects of metallization and heat treatment on thin gate oxide for use in sub-micron MOSFETs /." Full text open access at:, 1996. http://content.ohsu.edu/u?/etd,13.
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Nikiforov, Gueorgui Ognianov. "Current-induced Joule heating and electrical field effects in low temperature measurements on TIPs pentacene thin film transistors." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607814.
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Jones, Gavin B. "Investigating self-assembled monolayers and understanding small molecule/polymer blend thin-films in organic field-effect transistors." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/71007/.
Full textAbstract:
Organic Thin-Film Transistors (OTFTs) are now surpassing the performance of amorphous silicon based devices which once set the benchmark. State of the art development of OTFTs in active-matrix organic light emitting diodes (OLEDs) for flexible displays has shown the potential for future applications utilising organic materials. This unprecedented advancement of flexible base electronics is now at the forefront of research and development in the electronics industry. Although charge-carrier mobility has now exceeded expectations the processing of organic materials and device functionality is still under intense investigation. Through understanding energetic interactions and charge-carrier properties at the electrode/organic semiconductor (OSC) interface alongside morphological structuring of the thin-film active layer, a more complete understanding of OTFTs can be reached. Active layers formed of a soluble small molecule blended with a polymer binder have shown significant improvements in OTFT operational performance and device yield due to enhanced morphological effects. This thesis will primarily discuss the implementation of 6,13-bis(triisopropyl-silylethynyl) pentacene (TIPS-pentacene) blended with poly(4-methylstyrene) (P4MS) in the expectation of enhanced device performance offering heightened charge-carrier mobility. Through investigative work conducted in this thesis into self-assembled monolayer (SAM) formation on the source/drain electrodes (Chapter 3), changes in the surface properties of the metal contact and the resulting interfacial properties at the electrode/OSC interface are correlated to OTFT performance, alongside morphological changes in the active layer and its relation to charge-carrier conduction in TIPS/P4MS thin-films (Chapter 4). Additional studies concerning 2,8-difluoro-5,11–bis (triethylsilylethynyl) anthradithiophene (diF-TES-ADT) are also discussed (Chapter 5) relating to similar processing and fabrication conditions.
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Jaeger, Daniel J. "Investigation of sputtered hafnium oxides for gate dielectric applications in integrated circuits /." Online version of thesis, 2006. http://hdl.handle.net/1850/5194.
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劉志宏 and Zhihong Liu. "A study of thermally nitrided silicon dioxide thin films for metal-oxide-silicon VLSI techology." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1990. http://hub.hku.hk/bib/B31231895.
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Chen, kuan jen, and 陳冠任. "Study of New Generation Field-Effect Transistor and Thin-Film Transistor Technology." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/80139597613652112896.
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碩士<br>國立臺灣師範大學<br>光電科技研究所<br>97<br>Today, as MOSFET’s gate length getting small, to increase driving current and enhance gate control capability. in order to satisfy these requirements , It isn't comform to the semiconductor nowadays that SiO2 uses for gate oxide. Because the thickness of the insulator SiO2 will need to be reduced to small nanometer length, while keeping the EOT (equivalent oxide thickness) to maintain the characteristics of the devices. In the paper, in nanometer technology node, however, the electrons of the gate can flow through gate oxide into drain by tunneling in this place , and produce large leakage current . Using a new material with a dielectric constant greater than that of SiO2 to replace SiO2 film as gate dielectrics is an indispensable task.. Using insulators with high dielectric constant is one of the attractive and popular method to research the problem. Besides, SiGe materials has an important technique for improving the device performance other than conventional scaling method. Germanium can provide large mobility enhancement for CMOS. It will be of great importance to know the theoretical limit of mobility under various channel direction, and substrate orientation for device.
In this research, we use the anneal process and fabrication that get good quality of HfSiOx film and metal TiN. There are suppression of leakage current and reduce of oxide layer for the device.
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Chao-Yu, Meng. "Fabrication and Analysis of Poly-Si Thin Film Transistor and Si Nanowire Field Effect Transistor." 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2407200619491100.
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Meng, Chao-Yu, and 孟昭宇. "Fabrication and Analysis of Poly-Si Thin Film Transistor and Si Nanowire Field Effect Transistor." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/91299119763967689187.
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博士<br>國立臺灣大學<br>電機工程學研究所<br>94<br>The fabrication and analysis of poly-Si thin film transistor (TFTs) and Si nanowires (SiNWs) field effect transistor were studied in this thesis. The poly-Si with regular and large grain was fabricated by employing metallic pads as the heat sinks and with underlying silicon oxynitride (SiON) as the heat absorption layer. The TFTs fabricated by this method achieves a field effect mobility of 246 cm2/V-sec and an on/off current ratio exceeding 5×105. Besides, the degradation behavior of body-contact (BC) polysilicon thin film transistors under DC and AC stress were investigated and compared with conventional ones. It was found that the reliability of body-contact poly-Si TFTs is better than the conventional TFTs under both DC and AC stress conditions. After 1000s AC stress, the degradation of BC poly-Si TFTs become an order of magnitude less than the conventional ones. Therefore, a model was proposed to explain the degradation improvement of body-contact poly-Si TFTs.
The fabrication of SiNWs has been demonstrated using excimer laser annealed gold nanoparticles as the catalyst and vapor-liquid-solid (VLS) growth. Scanning electron microscopes images of the excimer laser annealed Au nanoparticles from 2.5, 5, and 10 nm Au film showed that the nanoparticles had mean diameters of 12, 13, and, 15nm, respectively. The results show that the diameter controlled uniform silicon nanowires can be obtained utilizing controlled thickness of Au film combined with suitable laser power density.
The un-doped and boron-doped SiNWs grown via VLS mechanism were studied. The diameters of un-doped and boron-doped SiNWs varied from 18.5 to 75.3 nm and 26.6 to 66.1 nm, respectively. The critical growth temperature of boron-doped SiNWs is 10 ℃ lower than that of un-doped ones and the diameters of the boron-doped SiNWs is always larger than that of the un-doped ones under different growth
temperatures. This is because that the introduction of diborane enhanced the dissociation of SiH4 which determines the growth process of SiNW.
Un-doped, N-type, and P-type doped SiNWs were grown at 460oC and 25 torr. The intensity ratio of anti-Stokes/Stokes (IAS/IS) peaks is used as an index of the sample temperature. Different SiNWs exhibit different Raman frequency shifts because their compressive stresses due to heating differ. The slopes of the IAS/IS peak ratio versus the Raman frequency for boron-doped, un-doped, phosphorous-doped SiNWs and bulk Si are -0.078, -0.036, -0.035 and -0.02 per cm-1, respectively. The different slopes reveal the different heating-induced compressive stresses in the SiNWs with different dopants and bulk Si.
The electric-field-directed growth of SiNWs was performed utilizing Au film with different thicknesses. It is found that the 1 and 0.5 nm Au film are more suitable for the electric-field-directed growth of SiNWs due to the formation of separated Au clusters during the thermal evaporation. Besides, the electric field in the range 0.5~2.5 V/μm are suitable for the direction controlled growth of SiNWs.
For further improvement of the position and direction controlled growth of SiNWs, the 20 nm Au nanoparticles were used as the catalyst to control the diameter of SiNWs. In the self-aligned structure, parts of the SiNWs across the gap become huger and the possible DC plasma enhance coating model is proposed to explain the phenomenon. It is also found that the position controlled structure with one sided Au catalyst is better and more suitable for the position and direction controlled SiNWs growth. Finally, the position and direction controlled SiNWs FETs were successfully fabricated by electric field directed growth. It demonstrates the feasibility to fabricate the SiNWs array and electrical devices with low cost.
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Li, Jeng-Ting, and 李政廷. "Polyaniline nanofibers thin film-based organic field-effect transistors." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/15175350295886008875.
Full textAbstract:
碩士<br>中原大學<br>奈米科技碩士學位學程<br>99<br>We investigate the electronic transport characteristics of HCl-doped polyaniline(PANI) nanofibers thin film-based transistor. The HCl-doped PANI nanofiber thin film is prepared by electrochemical synthesis and the thickness is controlled within 50nm. The current-voltage characteristic (ID-VD) and the resistivity of PANI channel layer is observed at a variety of temperature from 300 to 24K. We have found that the temperature dependence of the conductivity increases with reducing temperature on PANI channel layer by Efros–Shklovskii hopping conduction. The charge carrier reduced and Ambipolar transistor behavior can be observe dobviously after lowering the temperature. The HCl-doped PANI nanofibers thin film-based transistor work in enhancement mode with high electron mobility. Moreover ,we use the method of illumination to reduce carrier concentration.The electron mobility has been estimated in the linear region about 4.6 cm2/Vs at room temperature and reduces with lower temperatureas function of exponent.
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Hsieh, ping-heng, and 謝秉恆. "The Study on Ionic Sensitivity of CuInS2 Thin Film for Extended Gate Field Effect Transistor." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/28511733281178701598.
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Ji, Yan-Liang, and 季彥良. "The Study on Ionic Sensitivity of AgIn5S8 Thin Film for Extended Gate Field Effect Transistor." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/95685623246849388966.
Full textAbstract:
碩士<br>國立清華大學<br>材料科學工程學系<br>96<br>Recently, extended gate field effect transistor (EGFET) had been studied for pH meter or biosensor. In this study, the differences between EGFETs by NMOS and by PMOS were introduced. And, with the ion-sense membrane, AgIn5S8 thin films coated on ITO glass substrates by hydrothermal method, the ions-sensitivities were extracted by linear mode and by saturation mode in different concentration solutions of pH/p[Cu2+]/p[Pb2+]. The results show the sulfide film is sensitive to these kinds of ions. The ion sensitivities on membrane surface are 50.7mV/pH, 23.9mV/p[Cu2+], and 95.9mV/p[Pb2+] in NMOS-EGFET under applied bias-voltage 2.5V at reference electrode with saturation mode extraction. The membranes were also analyzed by electron spectroscopy for chemical analysis (ESCA), X-ray diffraction (XRD), and scanning electron microscopy (SEM), respectively. The analysis also shows good crystallinity of AgIn5S8 thin film.
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HUANG, PO-HAO, and 黃柏皓. "A Study of Effect of Drain Parasitic Field Plate on Amorphous InGaZnO Thin-Film Transistor." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/e8gwhq.
Full textAbstract:
碩士<br>國立雲林科技大學<br>電子工程系<br>106<br>In this work, 4-mask amorphous InGaZnO channel passivated TFT (a-IGZO CHP TFT) is simulated by technology computer aided design (TCAD), to investigate effects of source/drain (S/D) parasitic field-plates (FPs). Electrical characteristic and active layer carrier conduction are investigated to explore the corresponding physical mechanisms.
Influences of a-IGZO back surface damage induced by plasma-enhanced chemical vapor deposition (PECVD) passivation deposition and source/drain contact hole etching process would lead to defect created to cause the performance degradation and limit carriers transport. For this reason, to find a method to recover the TFT performance without using additional lithography processes is urgent. In this study, the device model is established based on a fabricated 4-mask a-IGZO CHP TFT by TCAD. Besides, we purposed a novel design which using the extended drain electrode as a parasitic FP or a virtual top-gate (TG) to improve the TFT performance.
Moreover, effects of parasitic S/D FPs on the TFT performance under different thicknesses of CHP (tCHP) and a -IGZO layer (tIGZO) will also be examined. Simulation results show that drain FP with an ideal can induce carriers in the a-IGZO layer to activate back channel conduction to enhance the TFT performance. However, to further understand the effects of the parasitic S/D FPs on the TFT I-V and performance. The corresponding physical mechanism verifies the validity of this simulated curves, current flow patterns and carrier concentration distribution will be explored.
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Liu, Ping-Jung, and 劉秉融. "Study of Tunneling-Field-Effect Poly-Si Thin-Film-Transistors." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/4awym3.
Full textAbstract:
碩士<br>國立臺灣科技大學<br>電子工程系<br>99<br>In the progress of the electronics industry, the scale down of conventional metal oxide semiconductor thin film transistor (MOSFET) will emerge some reliability problems, such as short-channel effect, hot- carrier effect and drain-induce barrier lowering (GIDL). When scale down of tunneling-field-effect transistor, it can make lower short-channel effect, hot-carrier effect and drain-induce barrier lowering. It can solve the reliability problems that it is scaled down.
Although tunneling-field effect transistor (TFET) can improve disadvantages of conventional MOSTFT, some issues of TFET are still need to be resolved. To obtain higher-performance TFET in this study, the design of new device structure and the analysis of device relative parameters are carried out via process and device simulation. Above this new device structure, a counter-doping pocket region enclosing the source region is formed. The performance of device is really improved by changing different dose and energy. From the simulation results, the newly designed TFET structures do have better performance than the conventional TFET.
TFET improves the leakage current problem of conventional MOSTFT that is produced in high scaling fabrication. Since there are not too many additional process steps compare with MOSFET, the new designed of TFET is an advancing device instead of MOSTFT in the future.
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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.<br>Thesis (Ph.D.)--Chinese University of Hong Kong, 2011.<br>Includes bibliographical references.<br>Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.<br>Abstract also in Chinese.
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"Fabrication and characterization of metallophthalocyanine-based organic thin-film transistors." 2008. http://library.cuhk.edu.hk/record=b5893462.
Full textAbstract:
Yu, Xiaojiang.<br>Thesis (M.Phil.)--Chinese University of Hong Kong, 2008.<br>Includes bibliographical references.<br>Abstracts in English and Chinese.<br>ABSTRACT (ENGLISH) --- p.I<br>ABSTRACT (CHINESE) --- p.III<br>ACKNOWLEDGEMENTS --- p.IV<br>TABLE OF CONTENTS --- p.V<br>Chapter 1. --- Overview of organic thin-film transistors (OTFTs) --- p.1<br>Chapter 1.1 --- Introduction to OTFTs --- p.1<br>Chapter 1.2 --- Basic mechanism of OTFTs --- p.4<br>Chapter 1.3 --- Applications of OTFTs --- p.6<br>Chapter 1.3.1 --- Driving of circuits for electronic papers and LCD --- p.6<br>Chapter 1.3.2 --- Light-emitting OTFTs --- p.8<br>Chapter 1.3.3 --- Sensing --- p.9<br>Chapter 1.4 --- Several key issues --- p.9<br>Chapter 1.4.1 --- Mobilities of OTFTs --- p.9<br>Chapter 1.4.2 --- Performance of bottom-contact OTFTs --- p.10<br>Chapter 1.4.3 --- Stability of OTFTs --- p.11<br>Chapter 1.4.4 --- Performance of n-type organic semiconductors --- p.13<br>Chapter 1.5 --- Why to study metallophthalocyanine-based OTFTs --- p.14<br>Chapter 1.6 --- Objective of this thesis --- p.17<br>References --- p.17<br>Chapter 2. --- Experimental details for fabrication and characterization of OTFTs --- p.22<br>Chapter 2.1 --- Purification of organic semiconductors --- p.22<br>Chapter 2.2 --- Preparation of the gate dielectrics for OTFTs --- p.24<br>Chapter 2.3 --- Deposition of organic thin films and gold source/drain electrodes --- p.26<br>Chapter 2.4 --- Process flow for the fabrication of OTFTs --- p.27<br>Chapter 2.5 --- Mobility measurement for the organic thin films --- p.28<br>Chapter 2.6 --- Characterization of organic thin films --- p.31<br>References --- p.31<br>Chapter 3. --- Optimizing the growth of VOPc thin films for high-mobility OTFTs --- p.33<br>Chapter 3.1 --- Experimental --- p.33<br>Chapter 3.2 --- Results and discussion --- p.34<br>Chapter 3.2.1 --- Growth of VOPc thin films on Si02 dielectric --- p.34<br>Chapter 3.2.2 --- Growth of VOPc thin films on Ta205 and Al203/Si02 dielectrics --- p.41<br>Chapter 3.4 --- Conclusion --- p.44<br>References --- p.45<br>Chapter 4. --- CuPc/CoPc and VOPc/CoPc p-type/p-type heterostructure OTFTs --- p.46<br>Chapter 4.1 --- CuPc/CoPc OTFTs in sandwich configuration --- p.47<br>Chapter 4.1.1 --- Experimental --- p.47<br>Chapter 4.1.2 --- Results and discussion --- p.48<br>Chapter 4.1.3 --- Conclusion --- p.57<br>Chapter 4.2 --- VOPc/CoPc OTFTs --- p.57<br>Chapter 4.2.1 --- Experimental --- p.57<br>Chapter 4.2.2 --- Results and discussion --- p.58<br>Chapter 4.2.3 --- Conclusion --- p.63<br>References --- p.64<br>Chapter 5. --- VOPc/F16CuPc p-type/n-type heterostructure OTFTs --- p.66<br>Chapter 5.1 --- Unipolar VOPc/F16CuPc OTFTs --- p.67<br>Chapter 5.1.1 --- Experimental --- p.67<br>Chapter 5.1.2 --- Results and discussion --- p.69<br>Chapter 5.1.3 --- Conclusion --- p.73<br>Chapter 5.2 --- VOPc/F16CuPc heterostructure for bottom-contact OTFTs --- p.74<br>Chapter 5.2.1 --- Experimental --- p.74<br>Chapter 5.2.2 --- Results and discussion --- p.74<br>Chapter 5.2.3 --- Conclusion --- p.77<br>References --- p.77<br>Chapter 6. --- Summary and future work --- p.80<br>Summary --- p.80<br>Future work --- p.81<br>References --- p.83<br>Appendix A: Capacitance-voltage (C-V) fitting for ITO/organic junction/AI devices --- p.85<br>Appendix B: Can electric-filed influence the growth of organic thin films? --- p.89<br>Appendix C: Micro-Raman study on organic thin films --- p.93<br>Appendix D: Publications which contributed to this thesis --- p.97
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Ko, Hsu, and 柯旭. "Fabrication of Pd/PdO thin film as sensing membrane for Extended Gate Field Effect Transistor (EGFET)." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/24115547390874272971.
Full textAbstract:
碩士<br>長庚大學<br>光電工程研究所<br>102<br>A palladium oxide (PdO) thin film pH sensor based on extended gate
filed effect transistor (EGFET) technique is fabricated and its pH sensing
properties, stability and reliability were studied. The thesis outlines the
procedures of converting palladium thin films into palladium oxide sensing
membrane. Pd thin film was first deposited by electron beam evaporation
technique on a sapphire substrate, followed thermal oxidation in furnace
with oxygen ambient. Comparisons were made among sensors with regards
to the effects of oxidation: reactive evaporation with oxidation, furnace
oxidation and two-step oxidation. First series of analysis has proven that
oxidation greatly enhances palladium’s sensitivity. Through further
temperature optimization, the averaged sensitivity of PdO sensor for pH
detection is approximately 62.87 mV/pH in concentrations among pH 2 to
pH 12. The hysteresis effect in 7→4→7→10→7 pH loop is about 7.9 mV.
The effect of long-term drift for PdO EGFET is 2.32 mV/hr in pH7 buffer
solution.
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Lin, Mic-Chen, and 林岷臻. "The Electrical Field Enhancement of Corner Effects on Thin-Film Transistor Nonvolatile Memories." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/41338917259055392516.
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碩士<br>國立交通大學<br>電子物理系所<br>99<br>For the first time, we propose a special structure to enhance the characteristic of TFT-SONOS memory devices. The memory process is not only simple but also compatible with 3D circuit integration. In this thesis, we investigate the effect of corners along channel width direction on TFT-SONOS memory. The experiments in this study used a local-oxidation of silicon (LOCOS) scheme to fabricate an M-shape in the width direction of TFT-SONOS memory. The programming and erasing operations are performed by the FN tunneling (FN) and Substrate transient hot-hole (STHH) injection, respectively. The improvement of M-shape TFT-SONOS memory is due to the locally electrical field enhancement at corners. On the other hand, the other advantage of this corner structure is the rounded corners improve the “Double Hump” situation. “Double Hump” would be caused by non-uniform charges injection.
Different oxidation thickness would make the platform and structure off-set of corners are different. The oxidation thicknesses are 100 nm and 150 nm, respectively. The more oxidation makes the higher structure off-set, but it is not direct related devices performance. We found out not the longer of effective width would depress the improvement of program/ erase speed.
The design exhibits superior electrical performance, including faster program/ erase speed, excellent data retention at high temperature, and width dependence. Thus, it has the larger application potential for flash memory market in the future.
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Hsu, Chia-wei, and 許家偉. "Channel Engineering of Tunneling-Field-Effect Poly-Si Thin-Film Transistors." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/71581049138535731102.
Full textAbstract:
碩士<br>國立臺灣科技大學<br>電子工程系<br>101<br>In the progress of the electronics industry, the scale down of conventional metal oxide semiconductor thin film transistor (MOSFET) will emerge some reliability problems, such as short-channel effect, hot- carrier effect, drain-induce barrier lowering (DIBL) and gate-induced drain leakage (GIDL). However, the scale down of tunneling-field-effect transistor would not encounter the above issues.
Although tunneling-field effect transistor (TFET) can improve disadvantages of conventional MOSTFT, some problems of TFET are still needed to be resolved. To obtain higher-performance TFET in this study, the design of new device structure and the analysis of device relative parameters are carried out via process and device simulation. The poly-SiC has a larger energy band gap than the poly-Si. Hence, the stacked poly-Si/poly-SiC channel layer can lead to a larger on-state current than the single poly-Si channel layer, due to higher electric field at source region.
On the other hand, the poly-SiGe has a smaller energy band gap than the poly-Si. Hence, the stacked poly-Si/poly-SiGe channel layer can show a larger current than the single poly-Si channel layer, whereas the stacked poly-Si/poly-SiGe channel layer would show a smaller off-state current than the single poly-SiGe channel layer.
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"Low-voltage organic thin film transistors (OTFTs) with solution-processed high-k dielectric cum interface engineering." 2013. http://library.cuhk.edu.hk/record=b5549763.
Full textAbstract:
儘管在提高有機薄膜晶體管（OTFTs）的性能方面已經取得了顯著地進步，但是由傳統二氧化矽介電層的低面電容密度引起的高驅動電壓一直是阻礙其在實際應用中發展的絆腳石。因此，開發具有低成本、高介電常數等特點的新型材料對於學術界和工業界都具有非常重要的意義。<br>本文首先介紹了一種簡單的溶液法在低溫下制備高介電常数的Al₂O{U+ABB7}/TiO{U+2093}（ATO）材料體系， 并詳細表徵和討論了它的介電性能。通過運用ATO作為介電層，我們成功地製備了低電壓銅酞菁（CuPc）基OTFT。有趣的是，該低電壓器件顯示出優異的性能，並且遠遠超過在二氧化矽上製備的器件性能。這個結果似乎和報道的結果相矛盾，因為高介電常數往往對器件性能造成不利影響。本文就此异常現象進行了詳細研究。基於初期生長的研究表明，在ATO表面上，CuPc分子組裝成有利於載流子輸運的棒狀晶體，并形成網狀結構。相反，在SiO₂表面上CuPc分子卻形成由無定形結構組成的孤立小島。此外，在ATO上還觀察到了更好的金屬/有機分子接觸，有利於載流子的注入。以上研究表明溶液法製備的ATO在实现高性能、低電壓的OTFT方面有著非常實用的前景。<br>此外，界面的性質對決定OTFT的電學性能非常關鍵。因此研究界面功能化對提高器件性能的作用也非常重要。在應用十八烷基磷酸（ODPA）和原位改性的Cu（M-Cu）分別對介電層/半導體、電極/半導體界面進行修飾后，并五苯（pentacene）基OTFT的電學性能得到大幅提高。此外，通過採用一薄層金覆蓋的M-Cu做電極（Au/M-Cu），器件性能得到進一步提升。本文就其詳細的機理進行了討論。<br>最后，由於具有低成本，可捲曲，可大面積加工等特點，柔性有機電子器件引起了廣汎關注。實現柔性OTFT的關鍵問題之一就是介電層同柔性襯底之間的結合。在此，我們成功地將ODPA和ATO集成到金覆蓋的柔性聚酰亞胺襯底上。通過使用Au/M-Cu做電極，柔性pentacene TFT顯現出優異的電學性能。另外，本文就器件的機械柔性及可靠性也做了詳細地探討，從而展示了一個實現低成本高性能柔性OTFT的有效途徑。<br>Although impressive progress has been made in improving the performance of organic thin film transistors (OTFTs), the high operation voltage resulting from the low gate areal capacitance of traditional SiO₂ remains a severe limitation that hinders OTFTs’ development in practical applications. In this regard, developing new materials with high-k characteristics at low cost is of great scientific and technological importance in the area of both academia and industry.<br>In this thesis, we first describe a simple solution-based method to fabricate a high-k bilayer Al₂O{U+ABB7}/TiO{U+2093} (ATO) dielectric system at low temperature. Then the dielectric properties of the ATO are characterized and discussed in detail. Furthermore, by employing the high-k ATO as gate dielectric, low-voltage copper phthalocyanine (CuPc) based OTFTs are successfully developed. Interestingly, the obtained low-voltage CuPc TFT exhibits outstanding electrical performance, which is even higher than the device fabricated on traditional low-k SiO₂. The above results seem to be contradictory to the reported results due to the fact that high-k usually shows adverse effect on the device performance. This abnormal phenomenon is then studied in detail. Characterization on the initial growth shows that the CuPc molecules assemble in a “rod-like“ nano crystal with interconnected network on ATO, which probably promotes the charge carrier transport, whereas, they form isolated small islands with amorphous structure onSiO₂. In addition, a better metal/organic contact is observed on ATO, which benefits the charge carrier injection. Our studies suggest that the low-temperature, solution-processed high-k ATO is a promising candidate for fabrication of high-performance, low-voltage OTFTs.<br>Furthermore, it is well known that the properties of the dielectric/semiconductor and electrode/semiconductor interfaces are crucial in controlling the electrical properties of OTFTs. Hence, investigation the effects of interfaces engineering on improving the electrical characteristics of OTFTs is of great technological importance. For the dielectric/semiconductor interface, an octadecylphosphonic acid (ODPA) self-assembled monolayer (SAM) is used to modify the surface of ATO (ODPA/ATO). For the electrode/semiconductor interface, a simple in-situ modified Cu (M-Cu) is employed as source-drain (S/D) electrodes in stead of commonly used Au. The electrical characteristics of pentacene TFT are drastically enhanced upon interfaces modification. Moreover, by encapsulating the M-Cu with a thin layer of Au (Au/M-Cu), the device performance is further improved. The detailed mechanism is systematically explored.<br>Finally, organic electronic devices on flexible plastic substrates have attracted much attention due to their low-cost, rollability, large-area processability, and so on. One of the most critical issues in realization flexible OTFTs is the integration of gate dielectrics with flexible substrates. We have successfully incorporated the ODPA/ATO with Au coated flexible polyimide (PI) substrate. By using Au/M-Cu as S/D electrode, the flexible pentacene TFTs show outstanding electrical performance. In addition, the mechanical flexibility and reliability of the devices are studied in detail. Our approach demonstrates an effective way to realize low-cost, high-performance flexible OTFTs.<br>Detailed summary in vernacular field only.<br>Detailed summary in vernacular field only.<br>Detailed summary in vernacular field only.<br>Detailed summary in vernacular field only.<br>Su, Yaorong.<br>Thesis (Ph.D.)--Chinese University of Hong Kong, 2013.<br>Includes bibliographical references.<br>Abstract also in Chinese.<br>Abstract --- p.i<br>Acknowledgement --- p.vi<br>Table of contents --- p.viii<br>List of Figure Captions --- p.xii<br>List of Table Captions --- p.xvi<br>Chapter Chapter 1 --- Introduction --- p.1<br>References --- p.6<br>Chapter Chapter 2 --- Background --- p.8<br>Chapter 2.1 --- Intrinsic electronic structure of small molecule semiconductors --- p.8<br>Chapter 2.2 --- Organic field-effect transistors --- p.13<br>Chapter 2.2.1 --- Architecture of OTFTs --- p.13<br>Chapter 2.2.2 --- Operation principles of OTFTs --- p.15<br>Chapter 2.3 --- Charge transport mechanisms --- p.20<br>Chapter 2.3.1 --- Band transport --- p.20<br>Chapter 2.3.2 --- Polaron transport --- p.22<br>Chapter 2.3.3 --- Hopping transport --- p.24<br>Chapter 2.3.4 --- Multiple trapping and thermal release (MTR) model --- p.26<br>Chapter 2.4 --- Parameters extraction --- p.29<br>Chapter 2.4.1 --- Current-voltage (I-V) characteristics --- p.30<br>Chapter 2.4.2 --- Field-effect mobility (μ) and threshold voltage (VT) --- p.31<br>Chapter 2.4.3 --- On/off current ratio and subthershold swing (SS) --- p.33<br>Chapter 2.4.4 --- Contact resistance (RC) --- p.35<br>Chapter 2.1.1.1 --- Origin of contact resistance --- p.35<br>Chapter 2.1.1.2 --- Extraction of contact resistance --- p.38<br>Chapter 2.1.1.2.1 --- Transfer line method (TLM) --- p.38<br>Chapter 2.1.1.2.2 --- Gated four-probe technique --- p.40<br>Chapter 2.1.1.2.3 --- Kelvin probe force microscopy (KPFM) --- p.42<br>Chapter 2.5 --- Gate dielectrics --- p.44<br>References --- p.47<br>Chapter Chapter 3 --- Materials and Experimental Techniques --- p.51<br>Chapter 3.1 --- Materials --- p.51<br>Chapter 3.2 --- Device fabrication procedures --- p.53<br>Chapter 3.3 --- Characterization --- p.55<br>Chapter 3.3.1 --- Electrical performance testing --- p.55<br>Chapter 3.3.2 --- Atomic force microscope (AFM) --- p.56<br>Chapter 3.3.3 --- Kelvin probe force microscopy (KPFM) --- p.58<br>Chapter 3.3.4 --- X-ray diffraction (XRD) --- p.60<br>Chapter 3.3.5 --- Grazing incidence X-ray diffraction (GIXD) --- p.63<br>Chapter 3.3.6 --- X-ray photoelectron spectroscopy (XPS) --- p.66<br>References --- p.71<br>Chapter Chapter 4 --- Solution-processed High-k Gate Dielectric --- p.73<br>Chapter 4.1 --- Introduction --- p.73<br>Chapter 4.2 --- Experimental details --- p.75<br>Chapter 4.3 --- Results and discussion --- p.77<br>Chapter 4.3.1 --- Structure of dielectric film --- p.77<br>Chapter 4.3.2 --- XPS characterization --- p.79<br>Chapter 4.3.3 --- Leakage current and capacitance --- p.80<br>Chapter 4.3.4 --- Low-voltage CuPc TFTs --- p.86<br>Chapter 4.4 --- Conclusion --- p.88<br>References --- p.88<br>Chapter Chapter 5 --- Study of CuPc OTFT with High-k Gate Dielectric --- p.91<br>Chapter 5.1 --- Introduction --- p.91<br>Chapter 5.2 --- Experimental details --- p.93<br>Chapter 5.3 --- Results and discussion --- p.95<br>Chapter 5.3.1 --- Devices electrical characteristics --- p.95<br>Chapter 5.3.2 --- Morphologies of dielectrics and CuPc fims --- p.99<br>Chapter 5.3.3 --- Crystal structure of CuPc films --- p.101<br>Chapter 5.3.4 --- Initial growth study --- p.102<br>Chapter 5.3.5 --- Surface energy characterization --- p.104<br>Chapter 5.3.6 --- In-plane structure of CuPc films --- p.105<br>Chapter 5.3.7 --- XPS characterization --- p.107<br>Chapter 5.3.8 --- KPFM study --- p.108<br>Chapter 5.3.9 --- Extended application to other materials --- p.110<br>Chapter 5.4 --- Conclusion --- p.113<br>References --- p.114<br>Chapter Chapter 6 --- Interface Engineering for High-performance Pentacene OTFTs --- p.117<br>Chapter 6.1 --- Introduction --- p.117<br>Chapter 6.2 --- Experimental details --- p.120<br>Chapter 6.3 --- Results and discussion --- p.121<br>Chapter 6.3.1 --- Leakage and capacitance of dielectric --- p.121<br>Chapter 6.3.2 --- Devices electrical characteristics --- p.123<br>Chapter 6.3.3 --- Contact resistance --- p.126<br>Chapter 6.3.4 --- Electrode/pentacene interface structure --- p.127<br>Chapter 6.3.5 --- XPS characterization --- p.129<br>Chapter 6.3.6 --- Proposed band diagram --- p.132<br>Chapter 6.3.7 --- Au encapsulation --- p.133<br>Chapter 6.4 --- Conclution --- p.136<br>References --- p.136<br>Chapter Chapter 7 --- Flexible Pentacene OTFTs --- p.140<br>Chapter 7.1 --- Introduction --- p.140<br>Chapter 7.2 --- Experimental details --- p.143<br>Chapter 7.3 --- Results and discussion --- p.146<br>Chapter 7.3.1 --- Leakage and capacitance characterization --- p.146<br>Chapter 7.3.2 --- Structure of pentacene thin film --- p.147<br>Chapter 7.3.3 --- Electrical properties of flexible OTFTs --- p.149<br>Chapter 7.3.4 --- Mechanical performance characterization --- p.152<br>Chapter 7.3.5 --- Ambient stability study --- p.158<br>Chapter 7.3.6 --- Study on the electrode structure --- p.160<br>Chapter 7.3.7 --- Study on the operational stability and lifetime --- p.163<br>Chapter 7.4 --- Conclusion --- p.166<br>References --- p.167<br>Chapter Chapter 8 --- Summary and Perspectives --- p.171<br>Chapter 8.1 --- Summary --- p.171<br>Chapter 8.2 --- Future work --- p.175<br>References --- p.177<br>Publications --- p.179
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Niu, Jing-Shiuan, and 牛敬璿. "Applications of Al2O3 Thin Film on Field-Effect Transistors and Gas Sensors." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/f52ptd.
Full textAbstract:
碩士<br>國立高雄師範大學<br>電子工程學系<br>107<br>In this dissertation, a series of AlGaN/AlN/GaN high electron mobility transistors (HEMTs) on silicon substrates and Al2O3 thin film-based resistor-type gas sensors are successfully fabricated and studied.
We first fabricated AlGaN/AlN/GaN HEMTs with Ni/Au gate electrode and focused on their properties. Then, nickel oxide (NiO) and aluminum oxide (Al2O3) layers are deposited by radio-frequency (RF) sputtering as gate oxide layers, respectively. Under the optimal process conditions, the improved device performance of the metal-oxide-semiconductor high electron mobility transistors (MOS-HEMTs) has been achieved. The DC characteristics of the MOS-HEMT with NiO and Al2O3 gate oxide layers include maximum drain-to-source saturation current densities IDS, max of 626.5 and 692.0 mA/mm, maximum transconductances gm, max of 87.6 and 94.2 mS/mm, gate-to-drain leakage currents IGD at VGD = -40 V of 1.47 10-7 and 8.21 10-11 mA/mm, threshold voltages Vth of -3.48 and -3.45 V, gate voltage swings GVS of 2.88 and 3.08 V, respectively. Due to the high dielectric constant, the gate dielectric layers can decrease the surface state density and drain-to-source resistance to cause sheet carrier concentration to increase.
Second, in order to improve the stability of the gate electrode under the thermal effects, we used palladium (Pd) metal to replace Ni/Au metal. After that, we inserted Al2O3 as the gate dielectric layer to develop a MOS-HEMT. The DC characteristics of the MOS-HEMT and MS-HEMT include IDS, max of 624.9 and 548.1 mA/mm, gm, max of 84.2 and 78.2 mS/mm, IGD at VGD = -40 V of 7.71 10-11 and 3.65 10-6 mA/mm, Vth of -3.13 and -4.28 V, GVS of 3.12 and 3.04 V, respectively. The experimental results show that the use of Pd metal as the gate electrode of HEMT has better thermal stability, allowing devices to obtain a larger operating range.
Then, five kinds of devices with the different metal gate electrodes and gate dielectric layers were fabricated and investigated. Experimentally, the device with the Pd gate electrode had lower gate leakage current and larger gate voltage swings than Ni/Au gate-electrode devices because Pd metal exhibits lower diffusion and higher thermal stability than Ni. Moreover, the gate dielectric layer can reduce interface charges and suppress gate leakage current to improve the device characteristics and reliability.
Finally, we deposited Al2O3 thin film on the interdigitated electrodes to fabricate a resistor-type gas sensor, which Al2O3 thin film is the sensing region. We used two different catalytic metals and structures. The first structure was the Pd nanoparticles (NPs)/Pd film/Al2O3 film and the second structure was the Pt NPs/Pt film/Al2O3 film. The experimental results showed that the sensing response ratios of the first structure are 14.4% in 1000 ppm H2/air and 15% in 20 ppm HCOH/air. The sensing response ratios are 8.2% in 1000 ppm NH3/air and -9.5% in 100 ppm NO2/air for the second structure, respectively.
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Tasi, Yi-Chan, and 蔡易展. "Phase Behavior and Thin-Film Properties for Solution-Processed Field-Effect Transistor Based on Liquid-Crystalline Semiconductor Oligothiophenes." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/99562959154036285179.
Full textAbstract:
碩士<br>國立暨南國際大學<br>應用化學系<br>98<br>In view of the increasing popularity of Organic Field Effect Transistor（OFET）. In order to implement the industrialization process, therefore, the solution process becomes an important of development goals. In this study, we used highly-soluble oligothiophene derivatives as organic active layer. These thin film were deposited by vacuum evaporation and solution process. In the vacuum evaporation process, we previous used to modify substrate surface by self-assembled monolayer（SAM）, octadecyltrichlorosilane（ODTS） and Hexamethyldisilazane（HMDS）. Then, rubbing to further improve the arrangement of SAM. The results of this series of results to that NTETB has the best electrical properties, the carrier mobility of up to 3.51×10-2 cm2/Vs and on/off current ratio is 4.04×102. Then, by atomic force microscopy and X-ray diffraction to investigate the relationship between film morphology, molecular arrangement and electrical property. Also because NTETB have the best performance, so a precursor of solution process in this study. After optimizing the conditions of the thin film, the carrier mobility of up to 5.79×10-2 cm2/Vs, but the leakage current was found. Then, using Differential Scanning Calorimeter（DSC） to measure the physical properties and through various heat treatment process. Finally, we analyze the thin film phase change process by polarized optical microscope and X-ray diffraction.
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Tseng, Shih-Hao, and 曾士豪. "Investigations on synthesis and ignition effect of single walled carbon nanotubes toward field emitter and thin film transistor." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/00374771002708566731.
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Yurchuk, Ekaterina. "Electrical Characterisation of Ferroelectric Field Effect Transistors based on Ferroelectric HfO2 Thin Films." Doctoral thesis, 2014. https://tud.qucosa.de/id/qucosa%3A28793.
Full textAbstract:
Ferroelectric field effect transistor (FeFET) memories based on a new type of ferroelectric material (silicon doped hafnium oxide) were studied within the scope of the present work. Utilisation of silicon doped hafnium oxide (Si:HfO2) thin films instead of conventional perovskite ferroelectrics as a functional layer in FeFETs provides compatibility to the CMOS process as well as improved device scalability. The influence of different process parameters on the properties of Si:HfO2 thin films was analysed in order to gain better insight into the occurrence of ferroelectricity in this system.
A subsequent examination of the potential of this material as well as its possible limitations with the respect to the application in non-volatile memories followed. The Si:HfO2-based ferroelectric transistors that were fully integrated into the state-of-the-art high-k metal gate CMOS technology were studied in this work for the first time. The memory performance of these devices scaled down to 28 nm gate length was investigated. Special attention was paid to the charge trapping phenomenon shown to significantly affect the device behaviour.:1 Introduction
2 Fundamentals
2.1 Non-volatile semiconductor memories
2.2 Emerging memory concepts
2.3 Ferroelectric memories
3 Characterisation methods
3.1 Memory characterisation tests
3.2 Ferroelectric memory specific characterisation tests
3.3 Trapping characterisation methods
3.4 Microstructural analyses
4 Sample description
4.1 Metal-insulator-metal capacitors
4.2 Ferroelectric field effect transistors
5 Stabilisation of the ferroelectric properties in Si:HfO2 thin films
5.1 Impact of the silicon doping
5.2 Impact of the post-metallisation anneal
5.3 Impact of the film thickness
5.4 Summary
6 Electrical properties of the ferroelectric Si:HfO2 thin films
6.1 Field cycling effect
6.2 Switching kinetics
6.3 Fatigue behaviour
6.4 Summary
7 Ferroelectric field effect transistors based on Si:HfO2 films
7.1 Effect of the silicon doping
7.2 Program and erase operation
7.3 Retention behaviour
7.4 Endurance properties
7.5 Impact of scaling on the device performance
7.6 Summary
8 Trapping effects in Si:HfO2-based FeFETs
8.1 Trapping kinetics of the bulk Si:HfO2 traps
8.2 Detrapping kinetics of the bulk Si:HfO2 traps
8.3 Impact of trapping on the FeFET performance
8.4 Modified approach for erase operation
8.5 Summary
9 Summary and Outlook