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1
Abusabee, K. M. "Thin film engineering for transparent thin film transistors." Thesis, Nottingham Trent University, 2014. http://irep.ntu.ac.uk/id/eprint/127/.
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Zinc oxide (ZnO) and Indium Gallium Zinc Oxide (IGZO) thin films are of interest as oxide semiconductors in thin film transistor (TFT) applications, due to visible light transparency, and low deposition temperature. There is particular interest in ZnO and IGZO based transparent TFT devices fabricated at low temperature on low cost flexible substrates. However, thermal annealing processes are typically required to ensure a good performance, suitable long term stability, and to control the point defects which affect the electrical characteristics. Hence there is interest in post deposition processing techniques, particularly where alternatives to high temperature thermal treatments can be utilised in combination with low temperature substrates. This thesis presents the results of a series of experimental studies as an investigation into photonic (excimer laser) processing of low temperature ZnO and IGZO thin films deposited by RF magnetron sputtering and/or by high target utilisation sputtering (HiTUS), to optimise the microstructure and electrical properties for potential use in thin film electronic applications. ZnO thin films were grown at various deposition parameters by varying oxygen flow rates, RF power, oxygen concentration, and growth temperatures. Subsequently, the films were subjected to three different annealing processes: (i) Thermal Annealing (furnace): samples were thermally annealed in air at temperatures ranging from 300 °C to 880 °C for 1 hour. (ii) Rapid Thermal Annealing: samples were annealed in nitrogen and oxygen environment at temperatures of 600 °C, 740 °C, 880 °C, and 1000 °C, and dwell times of 1-16 s. (iii) Excimer laser annealing: samples were annealed at ambient conditions using a Lambda Physik 305i 284 nm, 20 ns pulse KrF excimer laser with a beam delivery system providing a homogenised 10 mm x 10 mm uniform irradiation at the sample plane. Processing was undertaken at fluences in the range of 0 to 350 mJ/cm2 at single and multiple pulses. IGZO thin films were also investigated following RF magnetron deposition without intentional substrate heating and at various other deposition conditions, followed by laser processing in air at laser energy densities in the range of 0 to 175 mJ/cm2 with single pulse. Processed ZnO films were characterised by room temperature photoluminescence excitation which exhibited that laser annealing at high fluences resulted in suppression of the observed visible deep level emission (DLE) with evolution of a strong UV near band emission (NBE) peak, indicating a reduction of intrinsic defects without film degradation or materials loss that occurred by thermal and rapid thermal annealing. Also the intensity of the NBE peak was strongly influenced by the films growth temperature, with the results showing that as the growth temperature increased beyond ambient; the intensity of the resultant NBE peak decreased as a function of laser energy. TEM studies demonstrate that laser processing provides a controlled in-depth crystallisation and modification of ZnO films. Therefore, laser processing is shown to be a suitable technique to control the crystal microstructure and defect properties as a function of two lasers processing parameters (fluence, number of pulses) - realising optimised film properties as a localised region isolated from the substrate or sensitive underlying layers. In terms of electrical properties, the results indicated a significant drop in sheet resistance as a function of laser anneal from highly resistive (>5 MΩ/sq.) to about 860 Ω/sq. To produce IGZO thin films without intentional substrate heating with lowest sheet resistance as a function of laser processing, low deposition pressure, low oxygen concentration, and high RF power are required. Room temperature Hall effect mobility of 50 nm thick IGZO increased significantly as the laser energy density increased from 75 mJ/cm2 to 100 mJ/cm2 at single pulse reaching values of 11.1 cm2/Vs and 13.9 cm2/Vs respectively.
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Mackay, Ian. "Thin film electroluminescence /." Online version of thesis, 1989. http://hdl.handle.net/1850/10551.
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Han, Sanggil. "Cu2O thin films for p-type metal oxide thin film transistors." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/285099.
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The rapid progress of n-type metal oxide thin film transistors (TFTs) has motivated research on p-type metal oxide TFTs in order to realise metal oxide-based CMOS circuits which enable low power consumption large-area electronics. Cuprous oxide (Cu2O) has previously been proposed as a suitable active layer for p-type metal oxide TFTs. The two most significant challenges for achieving good quality Cu2O TFTs are to overcome the low field-effect mobility and an unacceptably high off-state current that are a feature of devices that have been reported to date. This dissertation focuses on improving the carrier mobility, and identifying the main origins of the low field-effect mobility and high off-state current in Cu2O TFTs. This work has three major findings. The first major outcome is a demonstration that vacuum annealing can be used to improve the carrier mobility in Cu2O without phase conversion, such as oxidation (CuO) or oxide reduction (Cu). In order to allow an in-depth discussion on the main origins of the very low carrier mobility in as-deposited films and the mobility enhancement by annealing, a quantitative analysis of the relative dominance of the main conduction mechanisms (i.e. trap-limited and grain-boundary-limited conduction) is performed. This shows that the low carrier mobility of as-deposited Cu2O is due to significant grain-boundary-limited conduction. In contrast, after annealing, grain-boundary-limited conduction becomes insignificant due to a considerable reduction in the energy barrier height at grain boundaries, and therefore trap-limited conduction dominates. A further mobility improvement by an increase in annealing temperature is explained by a reduction in the effect of trap-limited conduction resulting from a decrease in tail state density. The second major outcome of this work is the observation that grain orientation ([111] or [100] direction) of sputter-deposited Cu2O can be varied by control of the incident ion-to-Cu flux ratio. Using this technique, a systematic investigation on the effect of grain orientation on carrier mobility in Cu2O thin films is presented, which shows that the [100] Cu2O grain orientation is more favourable for realising a high carrier mobility. In the third and final outcome of this thesis, the temperature dependence of the drain current as a function of gate voltage along with the C-V characteristics reveals that minority carriers (electrons) cause the high off-state current in Cu2O TFTs. In addition, it is observed that an abrupt lowering of the activation energy and pinning of the Fermi energy occur in the off-state, which is attributed to subgap states at 0.38 eV below the conduction band minimum. These findings provide readers with the understanding of the main origins of the low carrier mobility and high off-state current in Cu2O TFTs, and the future research direction for resolving these problems.
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Hein, Moritz. "Organic Thin-Film Transistors." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-167894.
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Organic thin film transistors (OTFT) are a key active devices of future organic electronic circuits. The biggest advantages of organic electronics are the potential for cheep production and the enabling of new applications for light, bendable or transparent devices. These benefits are offered by a wide spectrum of various molecules and polymers that are optimized for different purpose.
In this work, several interesting organic semiconductors are compared as well as transistor geometries and processing steps. In a cooperation with an industrial partner, test series of transistors are produced that are intensively characterized and used as a basis for later device simulation. Therefore, among others 4-point-probe measurements are used for a potential mapping of the transistor channel and via transfer line method the contact resistance is measured in a temperature range between 173 and 353 K.
From later comparison with the simulation models, it appears that the geometrical resistance is actually more important for the transistor performance than the resistance of charge-carrier injection at the electrodes. The charge-carrier mobility is detailed evaluated and discussed. Within the observed temperature range a Arrhenius-like thermal activation of the charge- carrier transport is determined with an activation energy of 170 meV. Furthermore, a dependence of the electric field-strength of a Poole-Frenkel type is found with a Poole-Frenkel factor of about 4.9 × 10E−4 (V/m) −0.5 that is especially important for transistors with small channel length. With these two considerations, already a good agreement between device simulation and measurement data is reached. In a detailed discussion of the dependence on the charge-carrier density and from comparison with established the charge-carrier mobility models, an exponential density of states could be estimated for the organic semiconductor.
However, reliability of OTFTs remains one of the most challenging hurdles to be understood and resolved for broad commercial applications. In particular, bias-stress is identified as the key instability under operation for numerous OTFT devices and interfaces. In this work, a novel approach is presented that allows controlling and significantly alleviating the bias-stress effect by using molecular doping at low concentrations. For pentacene as semiconductor and SiO2 as gate oxide, we are able to reduce the time constant of degradation by three orders of magnitude. The effect of molecular doping on the bias-stress is explained in terms of the shift of Fermi level and, thus, exponentially reduced proton generation at the pentacene/oxide interface. For transistors prepared in cooperation with the industrial partner, a second effect is observed that can be explained by a model considering a ferroelectric process in the dielectric and counteracts the bias-stress behavior.
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Hu, Jingping. "Electronic Thin Film Materials." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491618.
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This thesis is concerned with investigations of the features of two types of electronic thin film materials: chemical vapour deposition (CVD) diamond and copper oxide based materials. CVD Diamond possesses excellent electrochemical properties. This thesis was concerned with investigating the fabrication and electrochemical properties of certain such diamond electrodes. The fabrication of diamond Ultramicroelectrodes (UMEs) was explored by coating tungsten needles with CVD diamond film under optimised. conditions, followed by selective insulation with different media. It was found that small grain diamond made the best electrode; large grain diamond coatings suffered from electrolyte leakage whereas nanodiamond had poor electrochemical properties. A range of tip insulation methods were examined, with most defined tips being produced by insulation with electrophoretic paint, followed by milling using Focused Ion Beam (FIB) methods. The utility of the tips prepared in this way in the SECM was demonstrated by imaging in biological media. The use of electrical conductive diamond as optically transparent electrode (OTE) opens novel applications for spectroelectrochemical studies due to the superior properties of diamond. The HFCVD diamond growth on fused silica quartz, ITO and AZO substrates was explored. The diamond membrane/ ITO structure was proposed and fabricated, exhibiting the best combination of optical transparency and electrical conductivity. Finally the changes in electrode properties as the diamond varied from macrocrystalline to nanocrystalline morphologies were studied. The second material investigated is copper oxide, specifically, cuprite (CU20) and SrCu202, a ternary Cu(I) oxide with a direct bandgap that arouses widespread interest as a p-type TCO. Their electronic structure and the nature of the hole charge carriers are topics of major current interest. The valence band and conduction band of both materials were studied by XPS in Daresbury, and XAS and XES measurements in ALS. The spectra are in good agreement with the PDOS from B3LYP calculations, showing strong hybridisation between Cu 3d and 0 2p states. Resonant Inelastic X-ray Scattering (RIXS) due to interband excitation close to Cu L3 edge threshold was first observed, conforming selection rule .6.L=O. This is the first observation of RIXS in close shell compound (dIO ). The UPS spectra of SrCu202 were measured with synchrotron radiation, and the changes in intensities of spectral features with varying photon energy were used to distinguish the contribution of 0 2p and Cu 3d states. Spectra showed that states at top of valance band are of dominant Cu 3d character and there is strong hybridisation between 0 2p and Cu 3d states which accounts for the hole mobility.
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Zhu, Wen Wei. "Organic thin film transistors." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19597.
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Organic thin film transistors (OTFTs) have been fabricated using four different semiconducting polymers: poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV), polyhedral oligomeric silsesquioxanes (POSS) poly (2-methoxy-5-(2'-ethyl-hexyloxy)-l,4-phenylene vinylene) (MEH-PPV-POSS), poly[N-(3-methylphenyl)-N,N-diphenylamine-4,4'-diyl] (poly-TPD), and polyhedral oligomeric silsesquioxanes (POSS) poly (N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine (poly-TPD-POSS). These OTFTs were fabricated on heavily doped «-type silicon wafers with thermally grown silicon dioxide layer was used as gate insulator. Except for MEH-PPV, the OTFTs studied in this work are the first for the above organic semiconductor materials. From results of current-voltage measurements, it was observed that the present OTFTs showed I-V characteristics of typical /^-channel thin film transistors. Some of the fabricated OTFTs showed performance with relatively large field-effect mobilities (>10~4 cm2 V"1 s"1). The mobility of semiconducting polymer with polyhedral oligomeric silsesquioxanes (POSS) was at least one order of magnitude larger than that of parent polymer without the POSS. The largest mobility value was obtained on poly-TPD-POSS (4.34 x 10"4 cm2 V"1 s"1) in room atmosphere and at room temperature. Thermal annealing under different conditions was carried out on the polymers and the effects on carrier field-effect mobilities were examined. The thermal annealing can increase slightly the field-effect mobilities of the polymers without POSS. However, no significant effect was observed on the field-effect mobilities of the polymers with POSS.
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McCaughan, Adam Nykoruk. "Superconducting thin film nanoelectronics." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/101576.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 163-171).
Superconducting devices have found application in a diverse set of fields due to their unique properties which cannot be reproduced in normal materials. Although many of these devices rely on the properties of bulk superconductors, superconducting devices based on thin films are finding increasing application, especially in the realms of sensing and amplification. With recent advances in electron-beam lithography, superconducting thin films can be patterned into geometries with feature sizes at or below the characteristic length scales of the superconducting state. By patterning 2D geometries with features smaller than these characteristic length scales, we were able to use nanoscale phenomena which occur in thin superconducting films to create superconducting devices which performed useful tasks such as sensor amplification, logical processing, and fluxoid state sensing. In this thesis, I describe the development, characterization, and application of three novel superconducting nanoelectronic devices: the nTron, the yTron, and the current-controlled nanoSQUID. These devices derive their functionality from the exploitation of nanoscale superconducting effects such as kinetic inductance, electrothermal suppression, and current-crowding. Patterning these devices from superconducting thin-films has allowed them to be integrated monolithically with each other and other thin-film superconducting devices such as the superconducting nanowire single-photon detector.
by Adam Nykoruk McCaughan.
Ph. D.
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Morasch, Kevin R. "Nanoindentation induced thin film fracture." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Thesis/Spring2005/k%5Fmorasch%5F042605.pdf.
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Geddis, Demetris Lemarcus. "Single fiber bi-directional OE links using 3D stacked thin film emitters and detectors." Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180141/unrestricted/geddis%5Fdemetris%5Fl%5F200312%5Fphd.pdf.
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Roos, Andreas. "Growth and characterization of advanced layered thin film structures : Amorphous SmCo thin film alloys." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-177674.
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This report describes the growth and characterization of thin amorphous samarium-cobalt alloy films. The samarium-cobalt alloy was grown by DC magnetron sputtering in the presence of an external magnetic field parallel to the thin film. The external magnetic field induces a uniaxial in-plane magnetic anisotropy in the samarium-cobalt alloy. The thin films were characterized with x-ray scattering, and the magnetic anisotropy was characterized with the magneto optic Kerr effect. The measurements showed a uniaxial in-plane magnetic anisotropy in the samarium-cobalt alloy films. It is not clear how amorphous the samples really are, but there are indications of crystalline and amorphous areas in the alloys.
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Marinkovic, Marko [Verfasser]. "Contact resistance effects in thin film solar cells and thin film transistors / Marko Marinkovic." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2013. http://d-nb.info/1037014243/34.
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Maka, Thorsten. "Thin film opal photonic crystals." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=974086991.
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Bjurström, Johan. "Advanced Thin Film Electroacoustic Devices." Doctoral thesis, Uppsala universitet, Fasta tillståndets elektronik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7672.
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The explosive development of the telecom industry and in particular wireless and mobile communications in recent years has lead to a rapid development of new component and fabrication technologies to continually satisfy the mutually exclusive requirements for better performance and miniaturization on the one hand and low cost on the other. A fundamental element in radio communications is time and frequency control, which in turn is achieved by high performance electro-acoustic components made on piezoelectric single crystalline substrates. The latter, however, reach their practical limits in terms of performance and cost as the frequency of operation reaches the microwave range. Thus, the thin film electro-acoustic technology, which uses thin piezoelectric films instead, has been recently developed to alleviate these deficiencies. This thesis explores and addresses a number of issues related to thin film synthesis on the one hand as well as component design and fabrication on other. Specifically, the growth of highly c-axis textured AlN thin films has been studied and optimized for achieving high device performance. Perhaps, one of the biggest achievements of the work is the development of a unique process for the deposition of AlN films with a mean c-axis tilt, which is of vital importance for the fabrication of resonators operating in contact with liquids, i.e. biochemical sensors. This opens the way for the development of a whole range of sensors and bio-analytical tools. Further, high frequency Lamb wave resonators have been designed, fabricated and evaluated. Performance enhancement of FBAR devices is also addressed, e.g. spurious mode suppression, temperature compensation, etc. It has been demonstrated, that even without temperature compensation, shear mode resonators operating in a liquid still exhibit an excellent performance in terms of Q (200) and coupling (~1.8%) at 1.2 GHz, resulting in a mass resolution better than 2 ng cm-2 in water, which excels that of today’s quartz sensors.
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Panda, Durga Prasanna. "Nanocrystalline silicon thin film transistors." [Ames, Iowa : Iowa State University], 2006.
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Qian, Feng. "Thin film transistors in polysilicon /." Full text open access at:, 1988. http://content.ohsu.edu/u?/etd,162.
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Bjurström, Johan. "Advanced thin film electroacoustic devices /." Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7672.
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Fuentes, Iriarte Gonzalo. "AlN Thin Film Electroacoustic Devices." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://publications.uu.se/theses/91-554-5557-3/.
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Murphy, Craig E. "Pyroelectric thin film composite materials." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260162.
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Grief, Andrew. "Modelling of thin-film superconductors." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432285.
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Guldeste, Ayhan. "Bismuth based thin film superconductors." Thesis, University of Oxford, 1994. http://ora.ox.ac.uk/objects/uuid:681efdc0-8cba-4b3d-83eb-e0021eea5135.
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This thesis describes investigations performed into the growth and characterisation of Bi-based (Bi2Sr2Can-1CunO2n + 4 + x, n=2, 3) ceramic superconducting material in the form of thin films, about 0.5μm thick, grown on single crystal MgO, LaAIO3 and SrTiO3 substrates by r.f. magnetron sputtering. The effect of oxygen content on the Pb doped Bi-2223 (n=3) phase was also studied by changing the cooling process and by annealing in different partial pressures of oxygen at ambient pressure. The films produced have been assessed by considering their initial composition where it is found that Bi/Sr ratios can be between 0.9
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Shard, Alexander Gordon. "Plasma assisted thin film formation." Thesis, Durham University, 1992. http://etheses.dur.ac.uk/5736/.
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Thin films of fluorocarbon-based polymers can be deposited by plasma assisted polymerisation of various perfluorocarbons. The chemical natures of plasma polymers of hexafluoropropene and perfluorohexane were examined as a function of power, flow rate and position in reactor. Polymerised hexafluoropropene displayed increased fluorine contents at high powers; this is at odds with perfluorohexane which demonstrated lower fluorine contents. Differing reaction mechanisms between saturated and unsaturated perfluorocarbons were proposed to explain this. Both perfluorocarbons were found to give increased CF(_2) contents out of the plasma glow region. This was demonstrated to be a function of distance from the monomer inlet, and was ascribed to the production of long lived polymer forming species in the gas phase. Plasma oxidation of low density polyethylene, polystyrene and poly (ether ether ketone) with oxygen and carbon dioxide was modelled by corresponding photooxidation reactions. Correlations between the structure of the polymer, the treatment used, and the final products were drawn. Aliphatic components tended to give carbon-oxygen single bonds, phenyl rings were oxidised to carbonyl and acid groups, and carbonyl groups to acids. Metal-containing polymeric thin films were produced from plasmas of zinc acetylacetonate and aluminium tri-sec -butoxide. The products from each monomer were different, with the zinc compound resulting in a high proportion of zinc carboxylate and the aluminium compound giving the oxide or hydroxide. Incorporation of these compounds into a perfluorohexane plasma resulted in the formation of metal fluoride containing thin films.
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Castaldi, Lorenzo. "Thin film rare earth magnets." Thesis, University of Sheffield, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289666.
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Gillanders, Ross Neil. "Optically addressed thin film sensors." Thesis, University of Strathclyde, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415379.
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Leslie, George Adam. "Thin-film flows on cylinders." Thesis, University of Strathclyde, 2012. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=18218.
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Three different problems concerning thin-film flows on horizontal cylinders are studied. Firstly, steady two-dimensional gravity-driven flow with prescribed volume flux of a thin film of Newtonian fluid with temperature-dependent viscosity (i.e. thermoviscous flow) over a uniformly heated or cooled stationary horizontal cylinder is studied. Numerical results along with asymptotic solutions in appropriate limits are presented giving an insight into the effects of thermoviscosity and heat transfer at the free surface. Next, we consider steady two-dimensional flow of a prescribed load (mass) of Newtonian fluid with temperature-dependent viscosity on a uniformly heated or cooled rotating horizontal cylinder. The existence of a critical solution with a critical load above which no solutions exist is found, and both this critical solution and the case of prescribed subcritical load are studied in detail, with both numerical and asymptotic solutions presented. In particular, it is found that back ow (i.e. flow counter to the direction of rotation) occurs within a certain region of parameter space (back ow never occurs in the corresponding isothermal problem). Finally, the steady isothermal flow of a symmetric thin slowly-varying rivulet of a non-perfectly wetting Newtonian fluid on either the outside or the inside of a uniformly rotating horizontal cylinder is considered. Numerical and asymptotic solutions in appropriate limits are presented and it is found that rivulet flow on a rotating cylinder gives rise to a critical solution similar in nature to the critical solution found for the classical two-dimensional problem. We also show that back flow occurs within a particular region of parameter space.
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Bauza, M. "Nanocrystalline silicon thin film transistors." Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1385744/.
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This thesis presents my work on the fabrication of nanocrystalline silicon (nc-Si) thin film transistors and characterization of their stability under different conditions. Nc-Si transistors are promising alternative to the current amorphous silicon (a-Si:H) devices, especially in areas where a-Si:H TFTs are reaching the performance ceiling, e.g. new large area applications such as active matrix organic light emitting diode displays (AMOLED). This is mostly due to the superior nc-Si properties – high carrier mobility and good electrical stability stemming from the crystalline Si grains embedded in a disordered a-Si:H matrix. Another large advantage of nc-Si TFTs over competing materials is the full compatibility with the a-Si:H fabrication base. Nanocrystalline silicon is a relatively new material and some aspects require further investigation before industrial applications. The pool of knowledge on nc-Si devices is especially shallow for the electrical stability of bottom gate TFTs under prolonged illumination which is important for several thin film applications, such as AMOLED and phototransistors. This issue was selected as the main topic of the thesis. Top gate TFTs were also designed, fabricated, characterized and compared to the bottom gate transistors. The electrically detected magnetic resonance method was employed to investigate the nc-Si/dielectric structures and it was shown that it can be used to evaluate the TG TFT channel/dielectric interface.
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McKinley, Iain Stewart. "Studies in thin film flows." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366911.
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Andreescu, Radu. "Exchange coupled thin film magnets /." Search for this dissertation online, 2004. http://wwwlib.umi.com/cr/ksu/main.
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Tam, Dickson Tai Shun. "An investigation on effect of Mn-doping on dielectric property of barium strontium stannate titanate." access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21175135a.pdf.
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Thesis (M.Sc.)--City University of Hong Kong, 2005.At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 4, 2006) Includes bibliographical references.
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Yeung, Kwok Fai. "An investigation on effect of Mn-doping on dielectric property of barium strontium stannate titanate." access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21175317a.pdf.
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Thesis (M.Sc.)--City University of Hong Kong, 2005.At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 4, 2006) Includes bibliographical references.
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Suttle, Helene. "Thin film vapour barrier systems on vacuum-planarized polyester films." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.555308.
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The work contained in this thesis examines how the properties of gas barrier materials may be affected by the choice of deposition technique, substrate material, and surface treatment. The performance of barriers with respect to the requirements for the optoelectronics industry was studied, along with an appraisal of the metrics used to assess barrier levels. Polyester films were coated with aluminium oxide by reactive sputter deposition in an industrial-scale research web coater. The transparency and stoichiometry of coatings was achieved by control of the reactive gas supply levels, and the deposition configuration in the web coater. Target poisoning, which leads to low deposition rates, was controlled by balancing the inert and reactive gases and by changing the reactive gas supply locations. Barrier properties of the films were found to be affected strongly by the choice of power supply. By using a method of depositing many thin layers of AIOx sequentially to build up a single layer, it was possible to extend the region of high barrier performance out to thick coatings of several hundred nanometres and thus create very high barrier materials. PEN (polyethylene naphtha late) film was used as a substrate material for all samples. It is a good candidate for use as a substrate for barrier films due to its excellent thermal, mechanical, and barrier properties. The use of surface treatments to minimise the effect of substrate surface features was examined. It was found that for coating thicknesses greater than 50 nm the surface smoothing layers did not improve barrier properties, and coated films with no smoothing layer performed better in water vapour transmission tests. Fragmentation tests showed that the barrier performance of films was greatly affected by the adhesion between the substrate and aluminium oxide coating. Various methods for measuring barrier film properties were studied in this work. The standard steady-state test for gas transmission rates was compared with the non-standardised calcium test. Organic photovoltaic (OPV) devices were encapsulated with barrier films to measure to what extent they act as a barrier to contaminants such as water vapour and oxygen. In a separate experiment, a component material of the OPV devices, poly(3-hexylthiophene) (P3HT), was used successfully in encapsulation tests where its degradation was measured using UV-vis-nIR spectrometry.
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Beringer, Douglas. "Thin Film Approaches to The Srf Cavity Problem: Fabrication and Characterization of Superconducting Thin Films." W&M ScholarWorks, 2016. https://scholarworks.wm.edu/etd/1499449840.
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Superconducting Radio Frequency (SRF) cavities are responsible for the acceleration of charged particles to relativistic velocities in most modern linear accelerators, such as those employed at high-energy research facilities like Thomas Jefferson National Laboratory’s CEBAF and the LHC at CERN. Recognizing SRF as primarily a surface phenomenon enables the possibility of applying thin films to the interior surface of SRF cavities, opening a formidable tool chest of opportunities by combining and designing materials that offer greater benefit. Thus, while improvements in radio frequency cavity design and refinements in cavity processing techniques have improved accelerator performance and efficiency – 1.5 GHz bulk niobium SRF cavities have achieved accelerating gradients in excess of 35 MV/m – there exist fundamental material bounds in bulk superconductors limiting the maximally sustained accelerating field gradient (approximately 45 MV/m for Niobium) where inevitable thermodynamic breakdown occurs. With state of the art niobium based cavity design fast approaching these theoretical limits, novel material innovations must be sought in order to realize next generation SRF cavities. One proposed method to improve SRF performance is to utilize thin film superconducting-insulating-superconducting (SIS) multilayer structures to effectively magnetically screen a bulk superconducting layer such that it can operate at higher field gradients before suffering critically detrimental SRF losses. This dissertation focuses on the production and characterization of thin film superconductors for such SIS layers for radio-frequency applications.
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Rauschmayer, Joseph T. "A complementary thin film process for digital applications." Ohio : Ohio University, 1985. http://www.ohiolink.edu/etd/view.cgi?ohiou1184074634.
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Xiong, Zhibin. "Novel scaled-down poly-Si thin-film transistor devices and technologies /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202005%20XIONG.
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Chow, Thomas. "A conduction model for intrinsic polycrystalline silicon thin film transistor based on discrete grains /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?ECED%202009%20CHOW.
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Wang, Yongjian. "Dewetting instability of polymer thin film /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202006%20WANG.
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Fogelström, Linda. "Polymer Nanocomposites in Thin Film Applications." Doctoral thesis, KTH, Ytbehandlingsteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12400.
Full textAbstract:
The introduction of a nanoscopic reinforcing phase to a polymer matrix offers great possibilities of obtaining improved properties, enabling applications outside the boundaries of traditional composites. The majority of the work in this thesis has been devoted to polymer/clay nanocomposites in coating applications, using the hydroxyl-functional hyperbranched polyester Boltorn® as matrix and montmorillonite clay as nanofiller. Nanocomposites with a high degree of exfoliation were readily prepared using the straightforward solution-intercalation method with water as solvent. Hard and scratch-resistant coatings with preserved flexibility and transparency were obtained, and acrylate functionalization of Boltorn® rendered a UV-curable system with similar property improvements. In order to elucidate the effect of the dendritic architecture on the exfoliation process, a comparative study on the hyperbranched polyester Boltorn® and a linear analogue of this polymer was performed. X-ray diffraction and transmission electron microscopy confirmed the superior efficiency of the hyperbranched polymer in the preparation of this type of nanocomposites. Additionally, an objective of this thesis was to investigate how cellulose nanofibers can be utilized in high performance polymer nanocomposites. A reactive cellulose “nanopaper” template was combined with a hydrophilic hyperbranched thermoset matrix, resulting in a unique nanocomposite with significantly enhanced properties. Moreover, in order to fully utilize the great potential of cellulose nanofibers as reinforcement in hydrophobic polymer matrices, the hydrophilic surface of cellulose needs to be modified in order to improve the compatibility. For this, a grafting-from approach was explored, using ring-opening polymerization of ε-caprolactone (CL) from microfibrillated cellulose (MFC), resulting in PCL-modified MFC. It was found that the hydrophobicity of the cellulose surfaces increased with longer graft lengths, and that polymer grafting rendered a smoother surface morphology. Subsequently, PCL-grafted MFC film/PCL film bilayer laminates were prepared in order to investigate the interfacial adhesion. Peel tests demonstrated a gradual increase in the interfacial adhesion with increasing graft lengths.QC20100621
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Inkoom, Godfred. "Ferromagnetic Resonance of LSMO Thin Film." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-12933.
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The magnetic properties of a 15uc thick LSMO thin film on SrTiO3 (STO) substrate atT=150K was investigated using the technique of ferromagnetic resonance (FMR). The FMRmeasurement of the 15uc thick LSMO thin film at a frequency f = 9.75GHz and powerP = 0.6325mW as a function of the angle between the static magnetic field H, and theeasy direction of magnetization within the sample plane in the "in-plane" (IP) configuration displayed an FMR spectrum. This resonance spectrum shows unequal resonance field peaks. The unequal peaks in the resonance field may be attributed to the uniaxial anisotropy field which satisfies the conditions for ferromagnetic resonance. The unequal peaks in the resonance field shows a maximum and minimum with negative and positive curvature which either increases or decreases with respect to the resonance field respectively. This increase or decrease in the resonance field depends on the magnetization direction. It has been shown that for a thick 15uc LSMO thin film at T = 150K the center position and the full width half maximum (FWHM) of the resonance field were 1070.1875 Oe and 159.3125 Oe respectively.
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Ma, Wen-Yuan, and 馬文元. "Transparent thin film transistors fabricated by amorphous InGaZnO4 thin films." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/33645187712147492214.
Full textAbstract:
碩士國立交通大學
電子物理系所
94
In this thesis, we study the transparent thin film transistors fabricated by amorphous InGaZnO4 (a-IGZO) thin films. The Hall measurements indicate that the carrier concentration of a-IGZO film is between 1019~1021 cm-3, resistivity ρ is around 10-3 (Ω-cm), and electron mobility is between 20~25 cm2V-1s-1 repectively. Films were deposited with O2 pressure between 20~200 mtorr. The contact between film and metal as well as indium-tin oxide (ITO) all showed the Schottky contact behavior. The devices, fabricated by a bottom gate structure combined with lift-off process at room temperature, show an average transmission (λ=400~700 nm) of 86.3%, saturation mobility μsat=7~19 cm2V-1s-1, on-off ratio reaches ~106, and low off current around 10-12A. The performances of devices are satisfactory for flat panel display applications. However, the non-linear characteristics of I-V and the current decay in large bias regime remain to be explored and improved.
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Lee, Chih-Hung, and 李至弘. "The Study of HfZnO Thin Film and Thin Film Transistor." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/03339234857014398090.
Full textAbstract:
博士國立臺灣大學
應用力學研究所
103
This thesis reports the properties of the HfxZn1-xO thin films deposited by rf-sputtering and sol-gel method. The sputter-deposited HfxZn1-xO thin films were then used as the active layers of thin film transistors (TFTs) on the glass substrates. The sputtering HfxZn1-xO thin films with various Hf contents are sputter-deposited on glass substrates from HfxZn1-xO (x = 0, 2.5, 5, 7.5 and 10 at%) targets at room temperature. The incorporation of Hf in the ZnO film leads to the amorphization of the materials. As the annealing temperature increases, the built-in stresses in the thin films are relaxed. The optical bandgap increases with the Hf content, yet it decreases with the annealing temperature. This can be attributed to the alteration of strain (stress) status in the films and the slight grain growth. Hf doping increases the resistivity of ZnO owing to the disorder of the material structure and the higher bandgap. The electrical properties of the rf-sputtered HfxZn1-xO/ZnO heterostructures were also investigated. A highly conductive interface is formed at the interface between HfxZn1-xO and ZnO thin films as the ZnO annealing temperature exceeds 500°C, leading to the apparent decrease of the electrical resistance. The resistance decreases with an increase of either thickness or Hf content of the HfxZn1-xO capping layer. The second part of thesis reports the characterization of sol-gel derived HfxZn1-xO thin films deposited on glass substrates. The incorporation of Hf in the films increases the crystallinity of the as-deposited films. The bandgap increases with the Hf content but reduces after thermal annealing because of the relaxation of built-in stress, atomic rearrangement, and precipitation of HfO2. The resistivity of ZnO decreases as the annealing temperature increases owing to the improvement of crystallinity and reduction of defect densities. On the contrary, the resistivity of HfxZn1-xO thin films increases with the annealing temperature owing to the precipitation of HfO2 and reduction of oxygen vacancies. The electrical properties of sol-gel derived Hf0.1Zn0.9O/ZnO and ZnO/HfxZn1-xO heterostructures were also investigated. The amount of resistance reduction increases as the bottom layer annealing temperature increases. According to the XPS result, the incorporation of Hf in the films improves the Zn-O bonding state, and thermal annealing enhances metal-oxygen bonding. Sputtered HfxZn1-xO (x=0.005, 0.01 and 0.025) is used as the channel layer of the bottom-gate TFT with MgO dielectric layer deposited by e-beam evaporation. The Hf0.005Zn0.995O shows the better device performance. The Vth, S.S., μlin and on-off ratio values for the Hf0.005Zn0.995O TFT were 4.1 V, 1.66 V/dec, 9.0 cm2/Vs and >107. In the top gate TFTs, Hf0.1Zn0.9O/ZnO hetertstructure is used as the channel of TFTs. The multilayer enhances the electrical properties of TFTs. The Vth, S.S., and μlin, values for the Hf0.1Zn0.9O/ZnO TFT were 0.38 V, 1.79 V/dec, and 158 cm2/Vs.
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Qin, Zhipei. "Thin film microextraction." Thesis, 2010. http://hdl.handle.net/10012/5170.
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This thesis developed thin film extraction technique, which is a solid phase microextraction (SPME) technique with enhanced sensitivity, without sacrificing analysis time due to the large surface area-to-volume ratio of thin film. Thin film extraction was applied for both spot sampling and time weighted average (TWA) sampling in laboratory and on site.
First, an electric drill coupled with a SPME polydimethylsiloxane (PDMS) fiber or a PDMS thin film was used for active spot sampling of polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Laboratory experiments demonstrated that the sampling rates of fiber and thin film can be predicted theoretically. The performance of a PDMS-coated stir bar at a constant stirring speed was also investigated. Compared with the fiber or the stir bar, the thin film sampler exhibited a higher sampling rate and much better sensitivity due to its higher surface-to-volume ratio and its larger extraction-phase volume. A new thin film active sampler was developed; field tests illustrated that it was excellent for rapid on-site water sampling due to its short sampling period, high sampling efficiency and durability.
Second, modeling was applied to study the kinetics of fiber SPME and thin film extraction by COMSOL Multiphysics. The symmetry of absorption of analyte onto the fiber (or thin film) and desorption of calibrant from the fiber in static aqueous solution and a flow through system, was demonstrated by modeling. Furthermore, kinetic calibration method was illustrated to be feasible for fiber SPME in complex aqueous matrix and then was used to calculate the total concentration of analyte in the system.
Third, thin film extraction was used in on-site sampling in Hamilton Harbour and for the determination of TWA concentrations of PAHs based on the kinetic calibration. When the thin film sampler, a fiber-retracted SPME field water sampler, and a SPME rod were used simultaneously, the thin film sampler exhibited the highest sampling rate compared to the other water samplers, due to its large surface-to-volume ratio.
Fourth, partition equilibriums and extraction rates of PAHs were examined for live biomonitoring with black worms and for the PDMS thin-film in passive sampling mode. In the initial extraction stage, the extracted amounts per surface area by two samplers were similar indicating that thin-film samplers could mimic the behavior of black worms for passive monitoring. A good linear relationship between bioconcentration factors and film-water partition coefficients of PAHs demonstrated the feasibility of thin-film sampler for determining the bioavailability of PAHs in water.
Finally, thin film extraction was used for the analysis of human skin and breath under different experimental conditions. Thin film technique could study several skin areas of one person, characterize the skins of different persons, and measure volatile fractions of cosmetic products that were released from the skin. The sampling time in the breath analysis could be further reduced to only 20 seconds when the thin film was rotated with a portable drill.
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Cooper, Ryan Christopher. "Thin Film Mechanics." Thesis, 2014. https://doi.org/10.7916/D8PR7T1V.
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This doctoral thesis details the methods of determining mechanical properties of two classes of novel thin films suspended two-dimensional crystals and electron beam irradiated microfilms of polydimethylsiloxane (PDMS). Thin films are used in a variety of surface coatings to alter the opto-electronic properties or increase the wear or corrosion resistance and are ideal for micro- and nanoelectromechanical system fabrication. One of the challenges in fabricating thin films is the introduction of strains which can arise due to application techniques, geometrical conformation, or other spurious conditions. Currently, inadequate models exist to model strain within thin films, making it difficult to produce structurally robust thin films and to prevent premature failure of a coating ordevice. It is thus imperative to understand and quantify thin film behavior under strain, both to aid in the development of new materials and processing techniques, as well as to enable the implementation of thin films into new designs. Chapters 2-4 focus on two dimensional materials. This is the intrinsic limit of thin films-being constrained to one atomic or molecular unit of thickness. These materials have mechanical, electrical, and optical properties ideal for micro- and nanoelectromechanical systems with truly novel device functionality. As such, the breadth of applications that can benefit from a treatise on two dimensional film mechanics is reason enough for exploration. This study explores the anomylously high strength of two dimensional materials. Furthermore, this work also aims to bridge four main gaps in the understanding of material science: bridging the gap between ab initio calculations and finite element analysis, bridging the gap between ab initio calculations and experimental results, nano scale to microscale, and microscale to mesoscale. A nonlinear elasticity model is used to determine the necessary elastic constants to define the strain-energy density function for finite strain. Then, ab initio calculations-density functional theory-is used to calculate the nonlinear elastic response. Chapter 2 focuses on validating this methodology with atomic force microscope nanoindentation on molybdenum disulfide. Chapter 3 explores the convergence criteria of three density functional theory solvers to further verify the numerical calculations. Chapter 4 then uses this model to investigate the role of grain boundaries on the strength of chemical vapor deposited graphene. The results from these studies suggest that two dimensional films have remarkably high strength-reaching the intrinsic limit of molecular bonds. Chapter 5 explores the viscoelastic properties of heterogeneous polydimethylsiloxane (PDMS) microfilms through dynamic nanoindentation. PDMS microfilms are irradiated with an electron beam creating a 3 m-thick film with an increased cross-link density. The change in mechanical properties of PDMS due to thermal history and accelerator have been explored by a variety of tests, but the effect of electron beam irradiation is still unknown. The resulting structure is a stiff microfilm embedded in a soft rubber with some transformational strain induced by the cross-linking volume changes. Chapter 5 employs a combination of dynamic nanoindentation and finite element analysis to determine the change in stiffness as a function of electron beam irradiation. The experimental results are compared to the literature. The results of these experimental and numerical techniques provide exciting opportunities in future research. Two dimensional materials and flexible thin films are exciting materials for novel applications with new form factors, such as flexible electronics and microfluidic devices. The results herein indicate that you can accurately model the strength of two dimsensional materials and that these materials are robust against nano-scale defects. The results also reveal local variation of mechanical properties in PDMS microfilms. This allows one to design substrates that flex with varying amounts of strain on the surface. Combining the mechanics of two dimensional materials with that of a locally irradiated PDMS film could achieve a new class of flexible microelectromechanical systems. Large-scale growth of two dimensional materials will be structurally robust-even in the presence of nanostructural defects-and PDMS microfilms can be irradiated to vary strain of the electromechanical systems. These systems could be designed to investigate electromechanical coupling in two dimensional films or for a substitute to traditional silicon microdevices.
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Chang, Ya-Yun, and 鄭雅云. "Growth of TiN and ZrO2 Thin Films Using Thin Film Templates." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/61382518230180369445.
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碩士國立清華大學
工程與系統科學系
97
This study developed a two-step method to control the growth of TiN and ZrO2 thin films using thin film templates and explored the effects of template on the structure and properties of the derivative thin films. The experiment was divided into two parts. The first part was to deposit TiN on TiN(111), TiN(200) and Ti(0002) templates. In the second part, ZrO2 thin films were grown by oxidizing ZrN thin films with different preferred orientations in Ar (99.99% purity) atmosphere, where ZrN (111) thin films were prepared by three deposition systems for examining the effect of different deposition methods. The texture of the top TiN thin films revealed by X-ray diffraction (XRD) changed from (111) to (200) as TiN(200) template was used. In the cases of using Ti(0002) or TiN(111) templates, the texture of the derivative TiN thin films switched from (200) to (111). The results indicated that templates were more effective on controlling texture of TiN thin film than adjusting deposition parameters. For the oxidation of ZrN thin film, monoclinic (m-ZrO2) and tetragonal (t-ZrO2) phases of ZrO2 were coexisted in all heat-treated specimens, and t-ZrO2 is the dominant phase in the ZrN specimen with higher N/Zr ratio while m-ZrO2 is prevailed in the ZrN specimens with lower N/Zr ratios. There was no substantial difference in the phase ratio and preferred orientation of m-ZrO2 grown from oxidation of ZrN specimens with different textures. Blisters were observed on the surface of the heat-treated ZrN specimens. A semi-quantitative analysis was proposed to examine the driving force of the blister formation, indicating that blisters may result from the compressive stress induced by the volume expansion from ZrN to m-ZrO2.
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Cho, Sungmee. "Nanostructured Thin Film Electrolyte for Thin Film Solid Oxide Fuel Cells." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-10145.
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Solid oxide fuel cells (SOFCs) are very attractive as energy generation devices because they are clean, reliable, and almost entirely pollution-free. SOFCs have flexible fuel selections compared with other fuel cell technologies. The main disadvantage of SOFCs is their high operating temperature (~1000ºC for conventional SOFCs) which leads to cell cracking and formation of non-conducting compounds at electrolyte/electrode interfaces. Therefore, intermediate temperature SOFCs (ITSOFCs) in the range of 500-700 ºC has attracted extensive research interests. To achieve high cell performance at reduced temperatures, it requires high-catalytic activity, high ionic conductivity, and comparable thermal expansion coefficient (TEC) of the cell components. To address the above issues, the research focuses on two main approaches (i.e., the interlayer approach and the electrolyte approach) in order to improve the overall cell performance. First, the design of a thin layer of a vertically-aligned nanocomposite (VAN) structure as an interlayer between the electrolyte and cathode is demonstrated. The development of the VAN structures consisted of the cathode material as a perovskite or ordered double perovskite structure, La0.5Sr0.5CoO3 (LSCO) or PrBaCo2O5 delta (PBCO), and the electrolyte material as a fluorite structure, Ce0.9Gd0.1O1.95 (CGO or GDC), were achieved for thin film solid oxide fuel cell (TFSOFCs). The VAN structure significantly improves the overall performance of the TFSOFC by increasing the interfacial area between the electrolyte and cathode and also acts as a transition layer that improves adhesion and relieves both thermal stress and lattice strain. Second, microstructural and electrical properties of Gd-doped CeO2 (GDC, Ce0.9Gd0.1O1.95) thin films electrolyte are studied for intermediate temperature solid oxide fuel cells (SOFCs). The GDC thin film electrolytes with different grain sizes and grain morphologies were prepared by varying the deposition parameters such as substrate temperature, oxygen partial pressure, target repetition rate, and laser ablation energy. The electrical property of the GDC thin film is strongly affected by the grain size. Third, bilayer electrolytes composed of a gadolinium-doped CeO2 (GDC) layer (~6 micrometer thickness) and an yttria-stabilized ZrO2 (YSZ) layer with various thicknesses (~330 nm, ~440 nm, and ~1 micrometer) are achieved by a pulsed laser deposition (PLD) technique for thin film solid oxide fuel cells (TFSOFCs). One effective approach is to incorporate YSZ thin film as a blocking layer in between the GDC and anode for preventing chemical reduction of GDC and electrical current leakage. This bilayer approach effectively improves the GDC's chemical/ mechanical stability and reduces the OCV loss under reducing conditions. The results suggest that the YSZ thin film serves as a blocking layer for preventing electrical current leakage in the GDC layer and also provides chemical, mechanical, and structural integrity in the cell, which leads to the overall enhanced performance.
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吳承哲. "Growth characterization of electrodeposited ZnO thin film on copper thin film." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/68932165056020424540.
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碩士建國科技大學
機械工程系暨製造科技研究所
98
The study uses magnetron sputtering to produce a copper thin film deposited on silicon substrates to provide a copper thin film substrate. Then electrochemical methods are adopted to investigate the properties of ZnO thin films. Aiming to understand the ZnO thin film deposited on copper thin film substrate, the study conducts experiments on various electrochemical parameters of ZnO. ZnO thin films are obtained via electrochemical deposition with controlled parameters such as concentration of electrochemical solution, voltage and temperature. X-ray Diffraction and scanning electron microscope are employed to examine and observe the crystal structure and surface properties of the thin film. The structural advantages and disadvantages of ZnO thin films are determined using Debye-Scherrer formula and texture formula. The findings of the experiment indicate that the presence of the ZnO buffer layer in the sample facilitates the crystal growth of ZnO, and optimal ZnO thin films can be obtained with temperature at 90oC, the concentration of zinc nitrate at 0.02M and with the presence of ZnO buffer layer.
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CHIU, YI-HSUN, and 邱奕勳. "Application of High Dielectric Hybrid Thin Films in Organic Thin Film Transistors." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/76348811197882023705.
Full textAbstract:
碩士明志科技大學
材料工程系碩士班
105
Organic thin film transistors (OTFTs) based on pentacene and hydroxyl-containing polyimide(PI)-SiO2-TiO2 hybrid films were fabricated on silicon substrate as the semiconductor and the gate dielectrics, respectively.The precursor was used to synthesize nano-sized SiO2-TiO2 colloid through the hydrolysis and condensation reaction in a sol-gel process. Then, PI-SiO2-TiO2 hybrid solution was synthesized from a condensation reaction between hydroxyl-containing SiO2-TiO2 and polyimide, followed by a spin coating to form the PI- SiO2-TiO2 dielectric composites. Cyclic olefin copolymer (COC) as a modify layer to modified the interface between the semiconductor and the dielectric layer. In addition, PffBT4T-2OD replace Pentacene as semiconductor, expect a good performance on device. The thermal, optical, surface, dielectric, and electrical properties of the PI-SiO2-TiO2 dielectric composites were investigated and correlated to the content of SiO2-TiO2, due to the dispersion and aggregation behaviors of the nanoparticles. The PI-SiO2-TiO2 hybrid dielectrics showed the tunable insulating properties, including high dielectric constants, high capacitances, and low leakage current densities. In addition, the bottom-gate top-contact OTFTs based on the PI-SrO2-TiO2 hybrid dielectrics showed the best performance with the near zero threshold voltage, PST40% and PST40%-COC showed the field-effect mobility (μ) about 7.39 cm2V-1s-1 and 9.72 cm2V-1s-1 and the current on/off ratio (Ion/ Ioff) about 2.5x104 and 1.4x104, respectively. Based on the above results, we are succeeded in the synthetic organic/inorganic hybrid thin film and the PST40% is the best performance among the films.
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Hsu, Chin-Tsar, and 許清茶. "The Study of Green Thin Film Electroluminescent Devices and ZnSe Thin Films." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/73390181103205789568.
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博士國立成功大學
電機工程研究所
82
In this thesis, the high luminous efficiency thin film electroluminescent devices and the characteristics of ZnSe thin films were investigated. The Ta2O5 and Al2O3 insulating have high resistivity that to act as current limiter. The HfO2 and BaTiO3 insulating have low resistivity that to act carrier injector. Crystallinity of the ZnS:Tb,F films deposited by RF- magnetron sputtering were studied by X-ray diffraction. The intensive diffraction line, which arises from (111) plane of zincblende structure, has been observed at around 28.5°. The spacing of (111) plane and latice constant of ZnS:Tb,F film are 3.12 A and 5.41 A, respectively. In order to evalute the interface properties of thin film electroluminescent device with stacked layer insulator structure, four kinds of samples with different insulating layers have been prepared. We found that that the EL device with a glass/indium tin oxide/BaTiO3/ ZnS:TbF3/HfO2/Ta2O5/HfO2/ Al structure exhibited higher brightness and higher efficiency than the other devices, because it has larger density of interface states and deeper interface states at HfO2/ZnS and BaTiO3/ZnS interfaces. The highest luminous efficiency and brightness of 0.9 lm/W and 1000 cd/㎡ were obtained, respectively, by applying a 1Khz sinusoidal wave viltage. The crystallinity of ZnSe thin films grown by MOCVD, which depends on the [H2Se]/[DMZn] mole ratio and substrate temperature was investigated. The full width at half maximum (FWHM) of X-ray Cu-Kα (111) ZnSe diffraction reaches the minimum value of 0.17°at optimal deposition condition. In this experiment, the optimal growth condition of ZnSe films are 300 ℃, 5 Torr and VI/II ratio of about 4. The latice constant and energy gap of ZnSe thin film obtained were 5.69 A and 2.70 eV, respectively. Absorption-edge shifts produced by an applied electric field (Franz-Keldysh) in ZnSe thin films have been studied. As a result, the absorption edge is shifted by about 33 meV toward longer wavelength.
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Tsai, Li-Shiuan, and 蔡立軒. "Nitrogen incorporated Hafnium Dioxide dielectric thin film For Organic Thin Film Transistors." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/05427454364168925544.
Full textAbstract:
碩士國立清華大學
材料科學工程學系
97
Hafnium oxide is a high-k dielectric material which have dielectric constant of 25,high-k dielectric material use to be a gate oxide can decrease the threshold voltage and device scale for low voltage and microelectronics. Organic thin film transistors has been used to fabricate soft electronics devices. The active layers for OTFTs is numerous, pentacene for our research is one of most used OTFTs active layers. In this thesis, we fabricate the HfO2 and HfON thin film by RF Reactive Magnetron Sputter System. The target is Hf metal for 99.99%, and we use Mass Flow Controller to put the Ar-O2-N2 mix gas in the chamber.HfO2 or HfON thin film would deposit on the substrate by Hf sputtering atoms react for O2 and N2.We deposit different recipes film to research their properties. Before depositing the dielectric film, we pre-deposit a Hf thin film. The thin film can decrease roughness for dielectric film, surface roughness decrease from Ra=1.972nm without Hf pre-sputtered to Ra=1.414nm with Hf pre-sputtered, this fabrication increase the device characteristics ,mobility increase from 0.086 cm2/V．s to 0.174 cm2/V．s, threshold voltage decrease from -0.7V to -0.31V,on-off ratio increase from 0.9x103 to 3.2x103, subthreshold swing decrease from -0.368 V/dec to -0.209 V/dec. In our research, a low surface energy dielectric film would have better device characteristics of pentacene based OTFTs. In this thesis, we deposit HfON thin film by Reactive Magnetron Sputter System, and make a OTFT device which have a better characteristics.
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TSAI, HUEI-JEN, and 蔡惠甄. "Characteristic Study of ITO Thin Film Etching and Cr Thin Film Evaporation." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/15506805664270546929.
Full textAbstract:
碩士南台科技大學
機械工程系
94
Abstract This study consists of two parts. The first part is to investigate four kinds of commonly used etching liquids to etch the thin film of indium tin oxide (ITO), and then compares the differences among them. When the ITO film is etched, the photo resistant layer usually serves as an etching mask to etch the required pattern. Therefore, it is necessary to find out the fastest way to etch the ITO film but almost not to etch the photo resistant layer. This study not only compares the etching rate of ITO film by four kinds of etching liquids at different temperatures and concentrations, but also measures the roughness of etched surface by an atomic force microscopy (AFM). Four kinds of etching liquids used in this study are HCl, HCl+H2O2, HCl+FeCl3 and (COOH)2·2H2O+H2O. Experimental results show that the four kinds of etching liquids have a faster etching rate at about 80°C and the highest concentration; their averages are 600, 450, 900, 37.5 nm/min, respectively. All etching liquids with lowest concentration lead to better surface roughness. The etching liquids HCl+H2O and HCl+H2O2 have better surface roughness of 0.4 nm and 0.6 nm, respectively, at 50°C; while (COOH)2·2H2O+H2O and FeCl3+HCl have better surface roughness of 0.03 nm and 0.5 nm at 80°C. The results of this study could be applied to the surface treatment of biochips that commonly use the ITO film as an electrode and to the combination of PDMS and ITO film glass. The second part of this study is to investigate metals as electrodes or conducting layers which are common used in the processes of micro-electro-mechanic-system (MEMS). Since the common used gold (Au) is difficult to affix on glass while evaporating, it needs a sticking layer to make gold adhere on glass. Therefore, common used metal chromium (Cr) is selected as sticking layers in this study. Evaporating rate, chamber temperature, and chamber vacuum are chosen as factors and an orthogonal array L9 with three levels is designed by Taguchi method. The changes of thin film characteristics and the quality of evaporated gold are examined by varying the parameters. Experimental results show that the condition of evaporating rate 0.5 Å/s, chamber temperature 21°C, and chamber vacuum 4.0´10-7 torr has better quality of thin film. Keywords: etching of ITO film, etching rate, roughness of etched surface, e-beam, evaporation, sticking layer, Taguchi method
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Rao, K. Yellareswara. "Sputter Deposited Thin Film Cathodes from Powder Target for Micro Battery Applications." Thesis, 2015. http://etd.iisc.ac.in/handle/2005/3825.
Full textAbstract:
All solid state Li-ion batteries (thin film micro batteries) have become inevitable for miniaturized devices and sensors as power sources. Fabrication of electrode materials for batteries in thin film form has been carried out with the existing technologies used in semiconductor industry. In the present thesis, radio frequency (RF) sputtering has been chosen for deposition of cathode material (ceramic oxides) thin films because of several advantages such as precise thickness control and deposition of compound thin films with equivalent composition. Conventional sputtering involves fabrication of thin film using custom made pellet according to the specification of sputter gun. However several issues such as target breaking are inevitable with the pellet sputtering. To forfend the issues, powder sputtering has been implemented for the deposition of various thin film cathodes in an economically feasible approach. Optimization of various process parameters during film deposition of cathode materials LiCoO2, Li2MnO3, LiNixMnyO4, mixed oxide cathodes of LiMn2O4, LiCoO2 and TiO2 etc., have been executed successfully by the present approach to achieve optimum electrochemical performance. Thereafter the optimized process parameters would be useful for selection of cathode layers for micro battery fabrication.
Chapter 1 gives a brief introduction to the Li ion and thin film solid state batteries. It also highlights the advantages of powder sputtering compared to conventional pellet sputtering.
In Chapter 2, the materials used and methods employed for the fabrication of thin film electrodes and analytical characterizations have been discussed.
In chapter 3, implementation of powder sputtering for the deposition of LiCoO2 thin films has been discussed. X-Ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS) and electrochemical investigations have been carried out and promising results have been achieved. Charge discharge studies delivered a discharge capacity of 64 µAh µm-1 cm-2 in the first cycle in the potential range
3.0-4.2 V vs. Li/Li+. The possible causes for the moderate cycle life performance have been discussed.
Systematic investigations for RF power optimization for the deposition of Li2-xMnO3-y thin films have been carried out. Galvanostatic charge discharge studies delivered a highest discharge capacity of 139 µAh µm-1cm-2 in the potential window 2.0-3.5 V. Thereafter, effect of LMO film thickness on electrochemical performance has been studied in the thickness range 70 nm to 300 nm. Films of lower thickness delivered higher discharge capacity with good cycle life than the thicker films. These details are discussed in chapter 4.
In Chapter 5, fabrication and electrochemical performance of LiNixMnyO4 thin films are presented. LMO thin films have been deposited on nickel coated stainless steel substrates. The as deposited films were annealed at 500 °C in ambient conditions. Nickel diffuses in to LMO film and results in LiNixMnyO4 (LMNO) film. These films were further characterized. Electrochemical studies were conducted up to higher potential 4.4 V resulted in discharge capacities of the order of 55 µAh µm-1cm-2.
In chapter 6, electrochemical investigations of mixed oxide thin films of LiCoO2 and LiMn2O4 have been carried out. Electrochemical investigations have been carried out in the potential window 2.0–4.3 V and a discharge capacity of 24 µAh µm-1cm-2 has been achieved. In continuation, TiO2 powder was added to the former composition and the deposited films were characterized for electrochemical performance. The potential window as well as the discharge capacity enhanced after TiO2 doping. Electrochemical characterization has been carried out in the potential window 1.4–4.5 V, and a discharge capacity of 135 µAh µm-1cm-2 has been achieved.
Finally chapter 7 gives overall conclusions and future directions to the continuation of the work.
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Rao, K. Yellareswara. "Sputter Deposited Thin Film Cathodes from Powder Target for Micro Battery Applications." Thesis, 2015. http://etd.iisc.ernet.in/2005/3825.
Full textAbstract:
All solid state Li-ion batteries (thin film micro batteries) have become inevitable for miniaturized devices and sensors as power sources. Fabrication of electrode materials for batteries in thin film form has been carried out with the existing technologies used in semiconductor industry. In the present thesis, radio frequency (RF) sputtering has been chosen for deposition of cathode material (ceramic oxides) thin films because of several advantages such as precise thickness control and deposition of compound thin films with equivalent composition. Conventional sputtering involves fabrication of thin film using custom made pellet according to the specification of sputter gun. However several issues such as target breaking are inevitable with the pellet sputtering. To forfend the issues, powder sputtering has been implemented for the deposition of various thin film cathodes in an economically feasible approach. Optimization of various process parameters during film deposition of cathode materials LiCoO2, Li2MnO3, LiNixMnyO4, mixed oxide cathodes of LiMn2O4, LiCoO2 and TiO2 etc., have been executed successfully by the present approach to achieve optimum electrochemical performance. Thereafter the optimized process parameters would be useful for selection of cathode layers for micro battery fabrication.
Chapter 1 gives a brief introduction to the Li ion and thin film solid state batteries. It also highlights the advantages of powder sputtering compared to conventional pellet sputtering.
In Chapter 2, the materials used and methods employed for the fabrication of thin film electrodes and analytical characterizations have been discussed.
In chapter 3, implementation of powder sputtering for the deposition of LiCoO2 thin films has been discussed. X-Ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS) and electrochemical investigations have been carried out and promising results have been achieved. Charge discharge studies delivered a discharge capacity of 64 µAh µm-1 cm-2 in the first cycle in the potential range
3.0-4.2 V vs. Li/Li+. The possible causes for the moderate cycle life performance have been discussed.
Systematic investigations for RF power optimization for the deposition of Li2-xMnO3-y thin films have been carried out. Galvanostatic charge discharge studies delivered a highest discharge capacity of 139 µAh µm-1cm-2 in the potential window 2.0-3.5 V. Thereafter, effect of LMO film thickness on electrochemical performance has been studied in the thickness range 70 nm to 300 nm. Films of lower thickness delivered higher discharge capacity with good cycle life than the thicker films. These details are discussed in chapter 4.
In Chapter 5, fabrication and electrochemical performance of LiNixMnyO4 thin films are presented. LMO thin films have been deposited on nickel coated stainless steel substrates. The as deposited films were annealed at 500 °C in ambient conditions. Nickel diffuses in to LMO film and results in LiNixMnyO4 (LMNO) film. These films were further characterized. Electrochemical studies were conducted up to higher potential 4.4 V resulted in discharge capacities of the order of 55 µAh µm-1cm-2.
In chapter 6, electrochemical investigations of mixed oxide thin films of LiCoO2 and LiMn2O4 have been carried out. Electrochemical investigations have been carried out in the potential window 2.0–4.3 V and a discharge capacity of 24 µAh µm-1cm-2 has been achieved. In continuation, TiO2 powder was added to the former composition and the deposited films were characterized for electrochemical performance. The potential window as well as the discharge capacity enhanced after TiO2 doping. Electrochemical characterization has been carried out in the potential window 1.4–4.5 V, and a discharge capacity of 135 µAh µm-1cm-2 has been achieved.
Finally chapter 7 gives overall conclusions and future directions to the continuation of the work.