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1
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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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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Mackay, Ian. "Thin film electroluminescence /." Online version of thesis, 1989. http://hdl.handle.net/1850/10551.
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Inameti, E. E. "Thermal studies of thin film fuses." Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234026.
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Neeves, Matthew Kenneth. "Thin film electrochromic materials and devices." Thesis, University of the West of Scotland, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627902.
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This thesis investigates in detail the thin film materials required for the construction of a thin film electrochromic device, their production by vacuum deposition and other techniques, and their characterisation by SEM, XRD, and optical and electrochemical methods, leading to a greater understanding of the materials and considerations required in the design of electrochromic layers and devices constructed with said layers. Working devices consisting of electrochromes, electrolytes and transparent conducting electrodes are constructed by methods and upon a scale that are amenable to commercial-scale production. The hardware and software components of a unique real-time spectroscopic electrochemical characterisation cell are described, which have enabled the novel synchronous collection of wideband optical transmittance and electrochemical information at intervals as small as 20ms. Optimal process conditions for the production of electrochromic transition metal oxides of nickel, titanium, tungsten and the novel nickel-chromium oxide by advanced sputtering and electron-beam evaporation techniques are investigated and described in-depth. For comparison, devices are also constructed using the well-known electrochromic material iron hexacyanoferrate, or 'Prussian Blue'. It is essential for devices intended for eyewear applications that materials are eye-safe and that traffic light recognition is not unduly impaired. The electrochromic performance of individual materials and working devices is reported for all materials and spectroscopic data is used to calculate tristimulus co-ordinates and thus characterise the colour performance of the various materials and devices. Working devices also require transparent conductive electrodes. The transparent conductive oxide indium tin oxide (ITO), as prepared by two different sputtering methods is investigated. The sheet resistance of the ITO is shown to have a significant quantifiable effect upon the switching speed of working devices and this is reported in detail.
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Hamblin, Mark Noble. "Thin Film Microfluidic and Nanofluidic Devices." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2281.
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Lab-on-a-chip devices, also known as micro total analysis systems (μTAS), are implementations of chemical analysis systems on microchips. These systems can be fabricated using standard thin film processing techniques. Microfluidic and nanofluidic channels are fabricated in this work through sacrificial etching. Microchannels are fabricated utilizing cores made from AZ3330 and SU8 photoresist. Multi-channel electroosmotic (EO) pumps are evaluated and the accompanying channel zeta potentials are calculated. Capillary flow is studied as an effective filling mechanism for nanochannels. Experimental departure from the Washburn model is considered, where capillary flow rates lie within 10% to 70% of theoretical values. Nanochannels are fabricated utilizing cores made from aluminum, germanium, and chromium. Nanochannels are made with 5 μm thick top layers of oxide to prevent dynamic channel deformation. Nanochannel separation schemes are considered, including Ogston sieving, entropic trapping, reptation, electrostatic sieving, and immutable trapping. Immutable trapping is studied through dual-segment nanochannels that capture analytes that are too large to pass from one channel into a second, smaller channel. Polymer nanoparticles, Herpes simplex virus type 1 capsids, and hepatitis B virus capsids are trapped and detected. The signal-to-noise ratio of the fluorescently-detected signal is shown to be greater than 3 for all analyte concentrations considered.
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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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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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Yilmaz, Koray. "Investigation Of Inse Thin Film Based Devices." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/3/12605431/index.pdf.
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In this study, InSe and CdS thin films were deposited by thermal evaporation method onto glass substrates. Schottky and heterojunction devices were fabricated by deposition of InSe and CdS thin films onto SnO2 coated glass substrates with various top metal contacts such as Ag, Au, In, Al and C. The structural, electrical and optical properties of the films were investigated prior to characterization of the fabricated devices.
The structural properties of the deposited InSe and CdS thin films were examined through SEM and EDXA analysis. XRD and electrical measurements have indicated that undoped InSe thin films deposited on cold substrates were amorphous with p-type conductivity lying in the range of 10-4-10-5 (
.cm)-1 at room temperature. Cd doping and post-depositional annealing effect on the samples were investigated and it was observed that annealing at 100 oC did not show any significant effect on the film properties, whereas the conductivity of the samples increased as the Cd content increases. Temperature dependent I-V and Hall effect measurements have shown that conductivity and carrier concentration increases with increasing absolute temperature while mobility is almost temperature independent in the studied temperature range of 100-430 K. The structural and electrical analysis on the as-grown CdS thin films have shown that the films were polycrystalline with n-type conductivity. Temperature dependent conductivity and Hall effect measurements have indicated that conductivity, mobility and carrier concentrations increases with increasing temperature. Transmission measurements on the as-grown InSe and CdS films revealed optical band gaps around 1.74 and 2.36 eV, respectively. Schottky diode structures in the form of TO/p-InSe/Metal were fabricated with a contact area of around 8x10-3 cm2 and characterized. The best rectifying devices obtained with Ag contacts while diodes with Au contacts have shown slight rectification. The ideality factor and barrier height of the best rectifying structure were determined to be 2.0 and 0.7 eV, respectively. Illuminated I-V measurements revealed open-circuit voltages around 300 mV with short circuit current 3.2x10-7 A. High series resistance effect was observed for the structure which was found to be around 588 &
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. Validity of SCLC mechanism for Schottky structures was also investigated and it was found that the mechanism was related with the bulk of InSe itself. Heterostructures were obtained in the form of TO/n-CdS/p-InSe/Metal and the devices with Au and C contacts have shown the best photovoltaic response with open circuit voltage around 400 mV and short circuit current 4.9x10-8 A. The ideality factor of the cells was found to be around 2.5. High series resistance effect was also observed for the heterojunction devices and the fill factors were determined to be around 0.4 which explains low efficiencies observed for the devices.
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Wingqvist, Gunilla. "Thin Film Electroacoustic Devices for Biosensor Applications." Doctoral thesis, Uppsala universitet, Fasta tillståndets elektronik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-89424.
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Biosensors are today important devices within various application areas. In this thesis a new type of label-free biosensor device is studied, which is fabricated using the same processes used for the fabrication of integrated circuits. This enables tighter integration and further sensors/biosensor miniaturization. The device is a so-called Thin Film Bulk Acoustic Resonator (FBAR). Within this thesis a low temperature reactive sputtering process for growing AlN thin films with a c-axis inclination of 20-30o has been developed. This enables shear mode FBAR fabrication suitable for in-liquid operation, essential for biosensor applications. Shear mode FBARs were fabricated operating at frequencies above 1GHz exhibiting Q values of 100-200 in water and electromechanical coupling factors kt2 of about 1.8%. This made it possible to move the thickness excited shear mode sensing of biological layers into a new sensing regime using substantially higher operation frequencies than the conventionally used quartz crystal microbalance (QCM) operating at 5-20MHz. Measured noise levels of shear mode FBARs in contact with water showed the resolution to be in the range 0.3ng/cm2 to 7.5ng/cm2. This demonstrated the FBAR resolution without any averaging or additional stabilization measures already to be in the same range as the conventional QCM (5ng/cm2), suggesting that FBARs may be a competitive and low cost alternative to QCM. The linear thickness limit for sensing of biomolecular layers was concluded to be larger than the thickness of the majority of the molecular systems envisaged for FBAR biosensor applications. A temperature compensated shear mode FBAR composite structure was demonstrated with retained coupling factor and Q-value by utilizing the second mode of operation. Understanding has been gained on the sensor operation as well as on how the design parameters influence its performance. Specifically, sensitivity amplification utilizing low acoustic impedance layers in the FBAR structure has been demonstrated and explained. Further, temperature compensated Lamb mode (FPAR) devices were also studied and demonstrated with optimized electromechanical couplings.wisenet
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Lau, S. P. "Thin film silicon carbide for electroluminescent devices." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637853.
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In this research, the optoelectronic and structural properties of thin film silicon carbide (SiC) prepared by plasma enhanced chemical vapour deposition and excimer (ArF) laser crystallisation are presented. These materials have been utilised as p-i-n electroluminescent devices, including development of various novel device structures. A wide-ranging series of experiments aimed at optimising the deposition conditions of amorphous and microcrystalline SiC films are described. Dark conductivity, photoconductivity, photoluminescence, optical absorption by Swanepoel's method and constant photocurrent method (CPM), scanning and transmission electron microscopy, infrared spectroscopy, and elastic recoil detection analysis were employed to characterise the films. Absorption spectra and the density of states profile of amorphous silicon carbide as found by CPM are reported. As the carbon content increases, the valence band tail becomes broader. At the same time, the deep defect density of states increases and also becomes broader. The CPM data also verified that the band gap widening is due to the conduction band shifting with increasing carbon content. It is shown that H2 dilution leads to an improvement of electronic properties via a decrease in the density of localised states. A novel method has been developed to prepare highly conductive and wide band gap doped microcrystalline silicon carbide (μc-SiC) by excimer (ArF) laser crystallisation. After crystallisation, this material has Tauc gap of around 2.0 eV and exhibits a dark conductivity as high as 20 (Ωcm)-1, more than ten orders of magnitude higher than before the laser irradiation. This is shown to be mainly correlated to structural change. The dopant concentration plays a dominant role in the electrical transport properties of μc-SiC, regardless of type of dopant and carbon concentration up to 30 at.%. Laser crystallised μc-SiC can be utilised not only as the carrier injection layer in a-SiC:H based electroluminescent devices, but also as a luminescent layer. EL devices fabricated with μc-SiC as a hole injector possess the highest electroluminescent intensity, the most stable emission and the longest operating life-time among all the investigated device structures. The electroluminescence from these devices is possibly related to the formation of some form of porous SiC by laser crystallisation.
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Ullah, Hanif. "Simulation studies of photovoltaic thin film devices." Doctoral thesis, Universitat Politècnica de València, 2015. http://hdl.handle.net/10251/48800.
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To cope with energy requirements the utilization of renewable energies, particularly the Sun supplies the biggest and abundant energy source in Earth. Photo-voltaic and solar cell are the well advance and burning technology and a field of hot research. Majority of research centers and universities are working in this field. 1G, 2G, 3G and next generation of photo-voltaic cells have been developed and still to improve its efficiency and to decrease it 0.2 $/W cost.
Our work mainly based on the theoretical and physical analysis of thin-film Photovoltaic devices. We will explore different software used for the analysis of PV cells, and will analyse different simulation related to solar cells like open circuit voltage VOC, Short circuit current JSC, Fill Factor FF (%) and external Quantum efficiency (%) for thin film solar cell including CIGS, CIS, CGS, CdTe, SnS/CdS/ZnO etc. To have different analysis for different combination and different replacement for materials used in the solar cell fabrication. To cope with the PV cost and environmental hazards we have to find alternate solutions.Ullah, H. (2015). Simulation studies of photovoltaic thin film devices [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48800
TESIS
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Zhang, Jiawei. "Oxide-semiconductor-based thin-film electronic devices." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/oxidesemiconductorbased-thinfilm-electronic-devices(c8cde776-b68b-47b5-ab63-382a86dbb94b).html.
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Oxide semiconductors have been envisaged to find applications in ubiquitous flexible electronics in daily life such as wearable electronic gadgets to offer novel user experiences. However, one of the bottlenecks to realise these applications is a lack of oxide-semiconductor components capable of wireless communications. As Bluetooth and Wi-Fi are the two dominant communication interfaces, fast enough front-end rectifiers must be developed to operate at their gigahertz (GHz) transmission frequencies. Furthermore, despite of significant developments of n-type oxide semiconductors in the last decade, widespread flexible electronics also requires high-performance p-type oxide semiconductors for use in complementary logic circuits. The objectives of this dissertation are to develop high quality Schottky barriers, achieve GHz speed Schottky diodes on rigid and flexible substrates, evaluate the noise properties of the Schottky diodes, develop p-type oxide semiconductor using sputtering technology, elucidate the hole transport mechanism in p type transistors, and demonstrate their potential applications such as radio receivers, complementary inverters and ring oscillators. First, indium gallium zinc oxide (IGZO) Schottky diodes were fabricated by using radio frequency magnetron sputtering. The oxygen content at the metal-IGZO interface was found to have a profound effect on the electrical performance. By introducing 3% O2 during the deposition of Pt or IGZO, the diodes exhibited excellent electrical properties without requiring any annealing treatment, thus allowing for the realisation of flexible IGZO Schottky diodes. The high-frequency properties of Pt-IGZO Schottky diodes on glass substrates were optimised by testing a range of IGZO thicknesses and diode active areas. The achieved highest cut-off frequency was beyond 20 GHz, which is to the best of our knowledge the fastest oxide-semiconductor device to date. On flexible substrates, the diodes also showed cut-off frequencies up to 6.3 GHz, well beyond the critical benchmark speed of 2.45 GHz for typical wireless communications. In order to assess the feasibility of using IGZO Schottky diodes in practical applications, measurements were taken to discern their low-frequency noise properties. In the as-deposited diodes, logarithmic dependence of the noise spectral density on the applied bias was observed, revealing that the dominant noise was generated in the space-charge region at low biases and in the series-resistance region at high biases, respectively. After annealing the diodes, very different noise mechanism was observed and the interface-trap-induced noise dominated the noise spectra. As one of the most promising p-type oxide semiconductors, SnO was also studied at low temperatures in this thesis. The experiment revealed that hole-transport mechanism was governed by either band conduction or variable range hopping in different temperature ranges. Finally, the potential for fully oxide-based electronics was demonstrated by an amplitude-modulation radio receiver comprising of an IGZO Schottky diode as the demodulator and a complementary ring oscillator based on IGZO and SnO transistors. In reference to IEEE copyrighted material which is used with permission in this thesis, the IEEE does not endorse any of the University of Manchester's products or services. Internal or personal use of this material is permitted. If interested in reprinting/republishing IEEE copyrighted material for advertising or promotional purposes or for creating new collective works for resale or redistribution, please go to http://www.ieee.org/publications_standards/publications/rights/rights_link.html to learn how to obtain a License from RightsLink.
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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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Calhoun, Kenneth Harold. "Thin film compound semiconductor devices for photonic interconnects." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/15478.
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Sethu, Murugesan. "Performance studies of thin film electroluminescent (TFEL) devices." Thesis, Nottingham Trent University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250453.
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Jiang, Hong Wen. "Piezoelectric thin film actuation of RF MEMS devices." Thesis, Cranfield University, 2004. http://dspace.lib.cranfield.ac.uk/handle/1826/10442.
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This thesis
investigates the piezoelectric thin film actuation of RF MEMS devices. lt is demonstrated that
piezoelectric actuation using silicon structures with integrated PZT thin film is suitable for RF MEMS
switches and mechanical filters. Both these devices are studied, fabricated and tested.
To assist the mechanical
design of a piezoelectric microswitch an electrical model is developed, from which
design parameters can be derived to meet the requirement of an insertion loss of -1dB and an isolation
loss of -40dB at 4GHz. The model shows how the
switching gap and the overlapping dimension are two
key parameters and the ratio between the two should be larger than 0.15. Switching gaps are chosen as
5m and 7.5m from the designed range of 3 ~ 15m. An equivalent circuit network incorporating a
transmission line model of the
coupling beam is developed to demonstrate a design method for the
mechanical filter. The model reveals that the
coupling beam stiffness, coupling position, electromechanical
coupling factor and the quality factor of the piezoelectric cantilever have substantial effects on filter
characteristics. A narrower/wider bandwidth with
higher/lower filter Q can result if the coupling position is
near/further to a cantilever's anchor
position. Extreme situations of the above two coupling cases result in
filter bandwidth's
disappearing and filter centre frequency's shifting. For a desired filter insertion loss
source and load resistances need to be determined
by quality factors of terminal circuit and coupled
resonators.
A bulk
micromachining process compatible with the integration of PZT thin film onto silicon is developed. ln
general, for PZT pattern size above 100m wet etching could give satisfactory pattern definition, however
for
pattern size below 50m dry etching is needed. To etch a thickness 2 1m PZT film long dry etching
lime demands for the
survivability of a masking material. ln this study a technique combined of dry and wet
etching is developed for a 1m PZT film. lt is found that a low pressure promotes a higher etch rate and
the best
etching conditions are a gas mixture with a composition of 1/4 for CHF3/Ar at a total gas flow of
25sccm under a RF
power of 150W. Dry etching is also developed to release cantilevers from the buried
S102 layer with conditions of a gas mixture of 13sccm CHF3 and 3sccm 02 at 80mTorr and a RF power of
100W in 30mins for 1m Si02. To be compatible with PZT elements silicon cantilevers are processed
using deep reactive ion etching.
PZT thin film actuation has been demonstrated
successfully with PZI' thin film integrated silicon
cantilevers. A static deflection of 2.89m is measured at an actuating voltage of 20V for a 100m wide and
450m long cantilever. A displacement of 556nm at 12.98 kHz resonance is measured for a 200m wide
and 850m long cantilever under a 10mV AC plus a 10V DC. A piezoelectric strain constant d31 of
30.15pC/N has been obtained for the PZT thin film used in this study. Filter resonant modes and
impedance responses are measured. The filter concept design is justified by the obtained results. Using
the
impedance data the electromechanical coupling factor, filter centre frequency, filter bandwidth and filter
Q are determined. There is a
good agreement between the measured and calculated filter centre
frequencies. At the first filter resonant mode a maximum piezoelectric coupling factor of 0.19 and a
maximum resonator-Q of 235 are recorded. At the second filter resonant mode a maximum of 0.12 and a
maximum resonator-Q of 360 are obtained. Results show smaller
coupling factors than required at the 13'
and 2" centre
frequencies for all measured filters. This implies that pass bands of designed filters will be
missing from their responses at the 18' and 2" centre frequencies. Design improvements are given in the
relevant results discussions.
Residual stresses are studied for deflected cantilevers after release. The tensile stress of PZT, the
converted tensile stress of Pt and the
compressive stress of remaining buried SiO2 layer could result in the
upwards-deflected cantilevers. The compressive stress of P could compensate the tensile stress of PZT
and flatten the cantilever beam. lf the buried SiO2 layer is removed incompletely or if the tensile stress of
PZT
layer is very high, then upwards-deflected cantilevers would result. Measurements of the most switch
cantilevers show
larger initial deflections than the designed switching gaps.
Finally, conclusions and suggestions of future work are given.
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Meakin, Douglas Boyd. "Active devices in polycrystalline silicon." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240344.
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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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Kung, Kenneth Ting-Yuan. "Polycrystalline Si thin films and devices : I. Seed selection through ion channeling II. Thin-film transistors." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/69699.
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Halverson, Adam Fraser. "The role of sulfur alloying in defects and transitions in copper indium gallium diselenide disulfide thin films /." Connect to title online (Scholars' Bank) Connect to title online (ProQuest), 2007. http://hdl.handle.net/1794/6193.
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Thesis (Ph. D.)--University of Oregon, 2007.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 127-132). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.
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Peeni, Bridget A. "Microfabrication and evaluation of planar thin-film microfluidic devices /." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1564.pdf.
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Ren, Huilin. "Current Voltage Characteristics of a Semiconductor Metal Oxide Sensor." Fogler Library, University of Maine, 2001. http://www.library.umaine.edu/theses/pdf/RenH2001.pdf.
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Berno, Bob. "The preparation, characterization, and application of thin film devices." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0003/NQ30269.pdf.
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Zhou, Yun. "Spin-dependent electron transport in nanomagnetic thin film devices." Thesis, University of Plymouth, 2011. http://hdl.handle.net/10026.1/556.
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Spin-dependent electron transport in submicron/nano sized magnetic thin film devices fabricated using the optical lithography, e-beam lithography and focused ion beam (FIB) was investigated with the primary aim to find the ballistic magnetoresistance (BMR) in thin film nanoconstrictions. All experimental results were analysed in combination with micromagnetic simulations. The magnetisation reversal processes were investigated in a submicron half-pinned NiFe stripe with a microconstriction. An asymmetric MR curve was observed, and micromagnetic simulations verified it was due to the exchange-bias on the left side, which changed the magnetic switching mechanism. The effects of different pinning sites on the magnetisation switching and domain wall displacement were studied in NiFe film and spin-valve based nanodevices. A sign of domain wall MR was seen on the transversal MR curve of the NiFe nanodevice due to the domain wall induced electron scattering. The size effect on the magnetisation switching and interlayer magnetostatic coupling was demonstrated and characterised in synthetic antiferromagnet (SAF)-pinned spin-valve nanorings. It has been clarified by micromagnetic simulations that these nanorings exhibit a double or single magnetisation switching process, which is determined by the magnetostatic coupling as a function of the ring diameter. The interlayer magnetostatic coupling was efficiently reduced in large SAF-pinned nanorings, resulting in a small shift of the minor MR curve, which is beneficial to the magnetic memory applications. In-situ MR measurements and the investigation of domain wall properties have been carried out in FIB patterned NiFe film nanoconstrictions. Spin-valve like sharp transitions were observed on the MR curves in the 80 nm/130 nm wide nanoconstriction devices. However, our analysis of the results by micromagnetic simulations and domain observations with scanning electron microscopy with polarisation analysis (SEMPA) concluded that these sharp MR transitions originated from the anisotropic magnetoresistance (AMR) effect, due to the fast magnetisation rotation in the nanoconstriction, and not from BMR. The numerical investigation has proved that a further reduction of the constriction width/length is necessary for large MR values.
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Craven, Marc Richard. "Increasing the performance of thin film electroluminescent (TFEL) devices." Thesis, Nottingham Trent University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324565.
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Mastio, Emmanuel Antoine. "Materials engineering for high efficiency thin film electroluminescent devices." Thesis, Nottingham Trent University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302407.
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Coe-Sullivan, Seth (Seth Alexander). "Hybrid organic/quantum dot thin film structures and devices." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33935.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 157-169).
Organic light emitting diodes have undergone rapid advancement over the course of the past decade. Similarly, quantum dot synthesis has progressed to the point that room temperature highly efficient photoluminescence can be realized. It is the purpose of this work to utilize the beneficial properties of these two material sets in a robust light emitting device. New deposition techniques are necessary to the realization of this goal, enabling QD organic hybrids to be created in a quick and reliable manner compatible with known device fabrication methods. With these techniques, quantum dot light emitting devices are fabricated, measured, and analyzed. The devices are of high efficiency and color saturation, and provide us with a test bed for understanding the interactions between inorganic QDs and organic thin films.
by Seth Coe-Sullivan.
Ph.D.
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Gasper, Michael Robert. "Characterizations and Applications of Carbon Nanotube Thin Film Devices." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1470304282.
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Peeni, Bridget Ann. "Microfabrication and Evaluation of Planar Thin-Film Microfluidic Devices." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/797.
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Over the past 15 years, research in the field of microfluidics has rapidly gained popularity. By seeking to miniaturize and automate separation-based analysis, microfluidic research seeks to improve current methods through decreased cost, analysis time, and sources of contamination. My work has focused on developing a novel fabrication method, based on standard microfabrication techniques, to create thin-film microfluidic devices. This microfabrication format makes it possible to generate devices that provide high efficiencies, enable mass fabrication, and provide a platform capable of integrating the microfluidic and electronic components necessary for a micro-total analysis system (μ-TAS). Device fabrication combines the processes of photolithography, thermal evaporation, plasma enhanced chemical vapor deposition (PECVD), and wet chemical etching to ultimately provide hollow-core channels. When these microcapillaries are filled with buffer and potentials are applied across them, control of the flow in the channels can be established. By designing intersecting microchannels having an offset “T†geometry, I have been able to inject and electrophoretically separate three fluorescently labeled amino acids and obtain efficiencies of over 2500 theoretical plates. Through the addition of commercially available electroosmotic flow reducing coatings, I have been able to improve the separation of these amino acids, decreasing the run time by approximately 6 fold and increasing the efficiency by as much as 10 fold. Through the use of these coatings I have also been able to carry out electrophoretic separations of three peptides. My most recent work has focused on the polymerization of acrylamide gels in these channels. A method for the selective placement of a gel has been developed using a prepolymer solution with a light-sensitive initiator. Further work to adjust the polymer pore size and interface with ampholyte-containing gels should allow methods such as capillary gel electrophoresis (CGE), preconcentration, and two dimensional (isolectric focusing and CGE) separations to be performed. The development of gel-based analysis methods, along with other fluidic and electrical capacities, should move thin-film microdevices toward the realization of the lab-on-a-chip concept.
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Sgambato, Kristopher. "Design and Testing of a Lateral Field Excited Rate Monitor for Use in Thin Film Deposition Systems." Fogler Library, University of Maine, 2009. http://www.library.umaine.edu/theses/pdf/SgambatoK2009.pdf.
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Baker, S. "Phthalocyanine Langmuir-Blodgett films and their associated devices." Thesis, Durham University, 1985. http://etheses.dur.ac.uk/7589/.
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Interest in the Langmuir-Blodgett (LB) technique has led to a number of investigations into different types of materials that can be deposited in the form of monolayers. For example, as well as the classic long Cham fatty acids and alcohols, materials such as polymerisable molecules, aromatic hydrocarbons and dye substances can now all be produced in monomolecular form. Unfortunately, few of these materials yet fulfil the requirements of mechanical and thermal stability that will be necessary if LB films are to be used commercially. This work has dealt with the use of phthalocyanine, a substance well known for its thermal and chemical stability, in the production of LB films. Initially two compounds were investigated, dilithlum phthalocyanine and tetra-tert-butyl phthalocyanine. Although it was found that both materials produced layers of reproducible quality which adhered tenaciously to various substrates and to each other, single monolayers were not obtained. More success has been achieved using an asymmetrically substituted phthalocyanine molecule. Electron microscopy studies have shown that the majority of films are polycrystalline. However, a substitute CuPc proved to be a valuable exception. Multilayer films of this molecule were found to have domains of the order of 3 mm in size showing a preferred orientation. Even so, it has to be accepted that the phthalocyanine films produced to date are not as structurally perfect as for example, multilayers of lo-tricosenoic acid. Our ability to produce monomolecular layers of phthalocyanine now extends the range of possible applications for this material. For instance it is known that the fine control of insulator thickness is crucial in the optimisation of photovoltaic and electroluminescent metal-lnsulator-semlconductor devices. Examples of both types of device have been demonstrated using our phthalocyaine films. For the bistable switch, a gallium arsenide substrate was used; both gallium phosphide and zinc selenlde have been utilized in the electroluminescent structures. Moreover, In the case of phthalocyanine another possibility presents Itself. It has long been known that the conductivities of this material and its derivatives are very sensitive to the presence of certain gases, particularly the oxides of nitrogen. The increased conductivity of such materials has been demonstrated to be confined to the surface of the crystal. Hence many phthalocyanine gas detector systems have been based on thin films. Unfortunately because phthalocyanine exhibits polymorphism, the exact structure of such films can be complicated. making interpretation of results and subsequent device optimisation difficult. Also the response and recovery times of these thin film devices can also be excessively long. It is possible that monomolecular LB films of phthalocyanine could well overcome some or all of these problems. Our experiments have concentrated on asymmetrically substituted copper phthalocyanine and its usefulness to detect nitrogen dioxide. Preliminary results show the response and recovery times for the simple gas structures to be faster than those previously reported for other thin film phthalocyanine devices. It is suggested that this is due to the more ordered structure of the LB film, which enables the gas to adsorb on, or desorb from the molecular sites more readily.
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Cheung, Yuk-fai, and 張煜輝. "Phosphor-free multilayered LEDs and thin film LEDs." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50900067.
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The irreversible trend of replacing the conventional incandescence light bulbs and fluorescent tubes with white light emitting diodes (LEDs) aims to use less energy for lighting. Plenty of the commercially available white LEDs are made from blue LED chips with few-micron-thick gallium nitride (GaN) grown on several hundred micron thick transparent sapphire substrates, followed by coating of yellow phosphor powder on top of the chips for converting the emitted blue light to white light. Not only does such approach give the white LEDs a high colour temperature, but also introduces conversion loss from the phosphor powder. The former issue makes users feel unpleasant for living while the latter wastes energy.
Therefore, a new version of phosphor-free multilayered vertically-stacked colour-tunable LED structure is proposed in this thesis such that it allows users to regulate the colour temperature of light source according to their preference. Simultaneously, the device replaces light conversion agents with direct light generation. The fabrication of the proposed device involved the use of backside laser micromachining of trenches on the substrates of the upper layers of basic colour LED chips at a size just enough to fit the wire-bonded wire of lower layer LED chips inside. With equal-sized basic colour LED chips tightly packed together, colour homogeneity of the proposed device is enhanced and thus provides the proposed device the capability to substitute the conventional RGB LED devices with basic colour LED chips separately aligned.
To improve the internal quantum efficiency and light extraction of nitride-based LEDs, thin film photonic crystal LED is proposed. Light and heat trapping sapphire substrate is removed by laser lift-off (LLO), forming GaN thin film on an electrically conductive opaque substrate with better heat conductivity than sapphire. By proper etching, N-dopped GaN layer can be exposed, resulting in the formation of vertical LED. Compared with conventional lateral LEDs with sapphire substrate, carrier path of vertical LED is greatly reduced and hence achieving lower internal resistance. To further boost light extraction, the device top surface is patterned with nanopillars by nanosphere lithography. A monolayer of closely-packed silica nanospheres is patterned on the N-GaN surface by spin coating. It acts as a mask for etching the nanopillars which bandfold lights from diffracted modes to radiative modes located above the light line for extraction.
A typical laser LLO process results in thin films with undopped gallium nitride (U-GaN) surface or N-GaN (after etching) faces up. If P-side up is necessary, the GaN layers are first required to attach to a temporary substrate for LLO and then the LLO exposed surface is adhered to the real substrate before temporary substrate is detached. This method is proposed to relieve the issue of light channeling inside the sapphire substrate of full colour LED micro-display panel fabricated on a single GaN on Sapphire wafer. With the elimination of sapphire, “parasitic” blue emissions from the area surrounding pixels are reduced which in turns improved the observable effects from the microspheres jet-printed on the top surface of the panel.published_or_final_version
Electrical and Electronic Engineering
Master
Master of Philosophy
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Liang, Cai Prorok Barton Charles. "Development of bulk-scale and thin-film magnetostrictive sensor." Auburn, Ala., 2007. http://repo.lib.auburn.edu/EtdRoot/2007/FALL/Materials_Engineering/Dissertation/Liang_Cai_15.pdf.
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Desai, Darshini. "Electrical characterization of thin film CdTe solar cells." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 320 p, 2007. http://proquest.umi.com/pqdweb?did=1257806491&sid=6&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Hunter, Kim R. "Macroscopic convection in the thin-film processor." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/45162.
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The thesis explores the proposal that macroscopic fluid convection in
thin-film processors may be adequately represented by simple linear
deterministic models. In addition, it examines the suggestion that the models
themselves provide a useful tool in the search for a generalizable 'intrinsic'
process heat transfer film coefficient, i.e., one that includes the effects of
axial dispersion of the process fluid. Such a parameter would be helpful in
the design and scale up of thin-film equipment.
The following approach was used to investigate this proposal: first,
experimental fluid residence time distributions were obtained t over a range of
operating conditions, using an industrial pilot plant thin -film processor. The
experimental data were used to select an appropriate linear fluid flow model for
the process. The model parameters were evaluated over this range using
frequency response techniques. These models were subsequently incorporated
into a numerical heat transfer simulation of the thin -film processor. Careful
matching of the pilot plant transient temperature responses to those predicted
by the simulation yielded the sought after intrinsic (dispersion corrected) heat
transfer film coefficients for the processor.
Master of Science
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Li, Bin, and 李斌. "A study of integrated semiconductor thin-film sensors on sio2/si substrate." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B30446752.
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Li, Bin. "A study of integrated semiconductor thin-film sensors on sio2/si substrate." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23000995.
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McDaid, Liam. "Electrical characterisation of silicon-on-insulator structures." Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385320.
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Larsson, Anna-Lena. "All-Thin-Film Electrochromic Devices for Optical and Thermal Modulation." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3917.
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Kim, Yunjo. "Two-dimensional material based layer transfer of thin film devices." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111747.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 40-42).
The semiconductor industry has mainly centered around silicon-based technology due to its associated cost advantage stemming from the abundance of the element and well-established fabrication infrastructures. However, there exists a plethora of compound semiconductors that offer unique electronic properties that can enable high performance devices superior to silicon for a wide range of device applications. Unfortunately, compound semiconductors industries have seen limited adoption in industries except in occasions where silicon-based technology cannot be used. This is mainly due to the rarity and high production costs associated with alternative semiconductor wafers. There have been many proposals that attempt to reduce the cost of production of these compound semiconductors by offering reusable wafers. In this scheme, the wafer is used as a platform to fabricate devices, the device layer is subsequently exfoliated from the wafer via a layer transfer allowing for the wafer to be re-used for continuous fabrication of thin-film devices. However, the layer transfer techniques that have been proposed so far often damages the wafer substrate, limiting their reusability and adding additional costs for surface refurbishment processes. This thesis proposes a novel layer transfer process, termed two-dimensional material based layer transfer (2DLT), which prepares thinfilm semiconductors by facile mechanical exfoliation to yield a clean wafer surface requiring minimal surface treatment. Moreover, this process can be applied to a wide range of material systems, suggesting a universal layer transfer process. The 2DLT process discussed in this work is enabled by a novel concept of semiconductor epitaxy, termed remote epitaxy. This thesis explores remote epitaxial growth of compound semiconductors on a graphene coated substrates and exfoliation of epitaxial films grown on graphene. Due to the atomic-thickness of graphene and weak van der Waals interaction on the surface of graphene, semiconductor adatoms on the surface of graphene can be made to register to the substrate for growth of single crystalline semiconductor films. In addition, the weak interactions at the interface of graphene provides a well-defined cleavage plane for facile mechanical exfoliation of the epitaxial film. This thesis investigates the conditions and mechanisms that facilitate remote epitaxy in order to identify the fabrication processes that enable 2DLT for compound semiconductors. The materials grown via remote epitaxy exhibited comparable properties to that of epitaxial films grown by conventional homoepitaxy, this has been demonstrated by fabrication of thin-film light emitting diodes (LEDs) and metal-semiconductor field-effect transistors (MESFETs), the results of which are presented in this work.
by Yunjo Kim.
S.M.
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Gupta, Man Prakash. "Numerical investigation of carbon nanotube thin-film composites and devices." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/54846.
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Carbon nanotubes (CNTs) are known for their exceptional electrical, thermal, mechanical, optical, and chemical properties. With the significant progress in recent years on synthesis, purification and integration challenges, CNT network/array based thin-film transistors (TFTs) are likely to play a critical role as the building blocks of future electronics. CNT-TFTs can find applications in flexible, transparent and energy-efficient circuits, e-displays, solar cells, RFID tags, e-paper, touch screens, implantable medical devices and chemical/bio/optical sensors. CNTs in CNT-TFTs are deposited on low thermal conductivity substrates which can impede the heat dissipation resulting in high temperature. The excessive self-heating in CNT-TFTs can degrade the electrical and thermal performance and could potentially lead to failure of the devices. Therefore, the issues related to operational reliability of CNT-TFTs arising from the self-heating effects need to be examined and studied. In the present work, a computational approach is developed and employed to study the electrical and thermal transport in CNT-TFTs. The modeling framework can predict the current and temperature profile of CNT network/array and the supporting structure. The model is validated against the experimental results. In case of CNT network TFTs, the computational method allows us to examine the role of various device parameters such as network morphology (i.e., network density, CNT junction topology, and CNT length and alignment distribution) and channel geometry (i.e., channel length and width) on heat dissipation and thermal reliability. The simulation results help interpret experimental data and provide the quantitative information about the thermal boundary conductances at CNT junctions and CNT-substrate interfaces in CNT-TFTs. The findings suggest that the structure of CNT junctions on substrate can become very critical in CNT network TFTs as the lack of contact with the substrate at these junctions can lead to junction temperatures hundreds of degrees higher than the rest of the device, which will severely deteriorate the performance of these devices. High-field breakdown study of CNT network TFTs is also conducted which provides guidelines for the design and optimization with respect to aforementioned parameters in order to enhance the performance and reliability. Dense CNT arrays are preferred for better electrical performance in CNT array TFTs, but they also experience electrostatic and thermal cross-talk which can adversely affect the device performance. These effects have been studied in details. The role of trap charges in CNT array TFTs is also investigated to understand and mitigate hysteresis. Lastly, CNT-liquid crystal composites are studied using dissipative particle dynamics (DPD) technique with the aim to understand how the CNT concentration in composite affects the alignment of liquid crystals and to explore the method of CNT alignment using liquid crystals.
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Jiang, Meng. "Processing and properties of nanostructured thin film energy storage devices." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:e651c635-6d92-4217-8442-43b2619c9c82.
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A spray deposition manufacturing route has been developed for the fabrication of carbon nano-structured and micro-structured energy storage devices in a thin film format, with controlled film thickness, homogeneous film surface morphology and high electrochemical performance for both supercapacitors and lithium ion battery anodes. Three types of low cost commercially available carbon materials (graphite, activated carbon and carbon black) have been investigated, and electrodes characterised in terms of surface morphology, surface chemistry, microstructure and electrochemical properties. By using ball milling, CO2 activation and adding suitable carbon conductive additives, nano-graphite-based film electrodes (one meter long and ~ 3 µm thickness) have been fabricated, with excellent ion transport and low electrical resistance (< 1.8 Ω). Specific capacitance of 110 F/g at a scan rate of 100 mV/s in 1 M H2SO4 was achieved. The high rate performance of activated carbon-based electrodes ( ~2 µm thickness) has been enhanced by reducing the contact resistance of electrode/current collector interface and building a well-interconnected and hierachical meso/macro-porous structure. A specific capacitance of over 120 F/g at a scan rate of 600 mV/s or 20 A/g current density in 1 M H2SO4 was achieved. The performance of carbon black-based electrodes (~4 µm thickness) in different electrolytes has been studied in both two- and three-electrode cells. High specific capacitances of 260 F/g at 1 A/g was achieved in 6 M KOH, together with energy and power densities of 21 kW/kg and 18 Wh/kg in 1 M Na2SO4. Finally, graphite-based electrodes for rechargeable lithium-ion batteries have also been fabricated with controlled film thickness from ~ 900 nm to ~ 40 µm and 98% capacity retention of 371 mA/g after 20 cycles. Spray deposition has been demonstrated to have the potential for scalability in the manufacture of carbon-based thin film electrodes with competitive properties.
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Saeed, Mahfouz Ali. "ELECTROCHEMICAL FABRICATION OF THIN FILM PHOTOVOLTAIC DEVICES (CIGS & CIGSS)." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1396265882.
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Balu, Venkatasubramani. "Barium strontium titanate thin film capacitors for high-density memories /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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McLaughlin, J. "Investigation of thin film properties of luminescent manganese doped zinc sulphide." Thesis, University of Ulster, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282979.
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Bergenek, Krister. "Thin-film photonic crystal LEDs with enhanced directionality." Thesis, St Andrews, 2009. http://hdl.handle.net/10023/912.
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