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Study on Electrical and Mechanical Characteristics of Flexural Plate Wave Device-Hung Chen, Yu 02 September 2010 (has links)
Acoustic micro-sensors have already been applied in mass sensing including surface acoustic wave (SAW), flexural plate wave (FPW), thickness shear mode (TSM) and shear horizontal acoustic plate mode (SH-APM). The FPW micro-sensor is very suitable for liquid-sensing and bio-sensing applications due to the high mass-sensitivity and low phase-velocity in liquid. However, the conventional FPW micro-sensors presented a high insertion-loss (IL) and a low signal-to-noise ratio so it is difficult to combine with IC into a micro-system.
To overcome these drawbacks, this study combine the Microelectromechanical System (MEMS) technology and the high C-axis orientation ZnO piezoelectric thin-film to develop a low insertion loss, low operation frequency, and high electromechanical coupling coefficient FPW device. In this study, a high C-axis orientation ZnO piezoelectric thin-film with a 20944A.U. X-Ray diffraction intensity at 34.200 degree and a 0.573 degree full width at half maximum (FWHM) was deposited by a commercial magnetic radio-frequency (RF) sputter system. The total processes of the FPW micro-sensor included five photolithography and seven thin-film depositions. In this study a low operation frequency (0.1MHz), low insertion loss (11dB to 14dB) and high electromechanical coupling coefficient (11%) FPW sensor was developed and fabricated.
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Synthesis and electrochemical characteristics of nitroxide polymer brushes for thin-film electrodesHung, Miao-ken 27 June 2012 (has links)
We reported a non-crosslinking approach to synthesize nitroxide radical polymer brushes for thin-film electrodes via surface-initiated atom transfer radical polymeization (SI-ATRP), which was effective to yield the organic radical polymer brushes with high grafting density and to attain a uniform surface. As mentioned above, the covalent bonding of nitroxide polymer brushes to the conducting substrate not only prevented the polymer dissolution into organic electrolyte solution but improved the cycle life performance of batteries. Moreover, they can be the potential application in microbatteries by using microcontact printing to produce the patterned nitroxide polymer brushes on a conducting substrate.
Even though the organic radical polymer brushes provided a new approach to syn-thesize thin-film electrodes, they still existed many problems that needed to study and to figure out. We discussed the morphology and electrochemical performance about ni-troxide radical polymer in the thesis. In the measurement of surface properties, we used the contact angle, electron spectroscopy for chemical analysis (ESCA) and atomic force microscopic (AFM) to proceed. Another, in the measurement of electrochemical analysis, we used the cyclic voltammetry(CV), alternating current (AC) impedance and charge-discharge to understand the regarding mechanism in this polymer layer during the electrochemical reaction.
In chapter 4, we discussed the oxidative problem in the polymer brushes. It should be well controlled during the oxidation reaction, because the oxidation level may affect the diffusion of electron that resulted the capacity better or not. In chapter5, we controlled the density of polymer brushes to construct the possible mechanism during the electro-chemical reaction, and found out the possible factors that affected the electrochemistry. In chapter 6, we applied the better results from the front chapter to the organic radical battery, and compared their electrical performance.
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Electrical Analysis and Physical Mechanisms of £\-InGaZnO Thin Film Transistors with different device structuresWu, Chang-Pei 12 July 2012 (has links)
The higher mobility is needed for thin film transistor (TFT) mainly used to be applied in the larger size flat-panel displays (FPDs). The amorphous metal oxide TFT has mobility higher than 10 cm2/V¡Es and can substitute the poor mobility (<1 cm2/V¡Es) of traditional amorphous silicon TFT, which shows a great potential for the next generation. Due to the superior characteristics in amorphous metal oxide TFT, therefore, the amorphous metal oxide TFT has been studied extensively.
Usually, the source/drain with island type device has a large overlapped/contact area that we cannot determine the exact electron path. That the sample of inverted stagger £\-IGZO TFTs with via type device has smaller contact area and can be estimated the electron path. In this thesis, the devices with different M1 overlaps etching stop layer (ESL) via distance, M2 £\-IGZO contact size and the fringe field effect are investigated. Although the characteristics of £\-IGZO TFTs have great performance, the electrical stability under illumination and long term bias stress are still a important issue to study before implement them into display. Thus, the devices with different structures that we mentioned previously are investigated the electrical reliability which are the negative bias stress of gate voltage, hot carrier stress effect and negative bias of illumination.
The electron path of via type is extracted by contact resistance which is greater than the distance between S/D via. Experiment results show that the increased offset between M1 and ESL via generates the resistance-liked effect in electrical characteristics. The hot carrier stress effect is independent of M2 £\-IGZO contact size in short channel length devices and there are close depletion lengths in drain side. The negative bias stress of illumination is proceeded in the fringe field effect devices, which results a negative shift of threshold voltage due to the hole trapping.
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Spin hall effect in paramagnetic thin filmsXu, Huachun 15 May 2009 (has links)
Spintronics, an abbreviation of spin based electronics and also known as
magneto electronics, has attracted a lot of interest in recent years. It aims to explore the
role of electrons’ spins in building next generation electric devices. Using electrons’
spins rather than electrons’ charges may allow faster, lower energy cost devices. Spin
Hall Effect is an important subfield of spintronics. It studies spin current, spin transport,
and spin accumulation in paramagnetic systems. It can further understanding of
quantum physics, device physics, and may also provide insights for spin injection, spin
detection and spin manipulation in the design of the next generation spintronics
devices.
In this experimental work, two sets of experiments were prepared to detect the
Spin Hall Effect in metallic systems. The first set of experiments aims to extract Spin
Hall Effect from Double Hall Effect in micrometer size metal thin film patterns. Our
experiments proved that the Spin Hall Effect signal was much smaller than the theoretically calculated value due to higher electrical resistivity in evaporated thin
films. The second set of experiments employs a multi-step process. It combines micro
fabrication and electrochemical method to fabricate a perpendicular ferromagnet rod as
a spin injector. Process description and various techniques to improve the measurement
sensitivity are presented. Measurement results in aluminum, gold and copper are
presented in Chapters III, IV and V. Some new experiments are suggested in Chapters
V and VI.
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Evaluating the Risk of TFT-LCD Industry-Cash Flow PerspectiveLiu, Shou-yuan 25 August 2005 (has links)
Abstract
With the critical development trend of industry of the world, TFT-LCD industry, following the footstep of semi-conductive industry, has become an important leading industry of Taiwan to the economic policy of the Government. The ¡§Two Trillion Double Star¡¨plan pro-
-moted by Industrial Development Bureau fo Taiwan intends to push up the production values of the two industries, semi-conductive and flat panel photonic displayer, to exceed NT$ 1 trillion respectively in 2006.
This plan also promotes digital contents and biotechnical industry to be
two star industries with high potentials of development. Therefore, TFT-
LCD industry is undoubtedly the core industry of the next wave of econo-
mic growth in Taiwan.
According to the distinguishing characteristics of capital and technology density, short-lived productive cycle, and variable productive technique in TFT-LCD industry, cash flow out of investment activities became the key point to promote the competitiveness with the continuously overcharge in the next generation panel field.In addition, the investors would find that the TFT-LCD panel factories have no ability to support the cash flow out which invested in equipment if they do not ask for finance.
In this paper, we attempt to investigate the relationship between variation of cash flow in operation, investment, and finance activities and potential risk of operation in enterprise by financial statement in TFT-LCD industry. In addition, this dissertation commence with ROE and development from Du-Pont Formula. Our research decomposes ROE to fundamental elements in enterprise step by step, such as the construction of cost and expense and the risk of business. Furthermore, we afford a referable approach to estimate performance of companies by Du-Pont Formula.
Key Words¡G
Thin Film Transistor (TFT), Liquid Crystal Display (LCD),Cash Flow, Risk, Risk Management, Du Pont Equation, Du Pont Ratio.
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1066 |
Production Of Hydrogenated Nanocrystalline Silicon Based Thinfilm TransistorAliyeva, Tamila 01 July 2010 (has links) (PDF)
The instability under bias voltage stress and low mobility of hydrogenated amorphous
silicon (a-Si:H) thin film transistor (TFT), produced by plasma enhanced chemical vapor deposition
(PECVD) technique, are the main problems impeding the implementation of active
matrix arrays for light emitting diode display panels and their peripheral circuitry. Replacing
a-Si:H by hydrogenated nanocrystalline silicon film (nc-Si:H) seems a solution due to its
higher mobility and better stability. Therefore nc-Si:H TFT was produced and investigated in
this thesis.
All TFT layers (doped nc-Si:H, intrinsic nc-Si:H and insulator films) were produced separately,
characterized by optical (UV-visible and FTIR spectroscopies, XRD) and electrical
(current-voltage, I-V) methods, and optimized for TFT application. Afterwards the non
self-aligned bottom-gate TFT structure was fabricated by the photolithographic method using
2-mask set.
The n+ nc-Si:H films, used for TFT drain/source ohmic contacts, were produced at high
H2 dilution and at several RF power densities (PRF). The change of their lateral resistivity
(rho) was measured by reducing the film thickness via reactive ion etching. The rho values rise
below a critical film thickness, indicating the presence of the disordered and less conductive
incubation layer. The optimum PRF for the lowest incubation layer was determined.
Among the deposition parameters only increased NH3/SiH4 flow rate ratio improved the
insulating properties of the amorphous silicon nitride (a-SiNx:H) films, chosen as the TFT
gate dielectric. The electrical characteristics of two TFTs with a-SiNx:H having low leakage
current, fabricated at different NH3/SiH4 ratios (~19 and ~28) were compared and discussed.
The properties (such as crystallinity, large area uniformity, etc.) of the nc-Si:H film as
TFT channel layer, were found to depend on PRF. For the films deposited at the center of
the PECVD electrode the change from an amorphous dominant structure to a nanocrystalline
phase took place with increasing PRF, whereas those at the edge had always nanocrystalline
nature, independent of PRF. The two different TFTs produced at the center of the electrode
with a-Si:H and nc-Si:H grown at low and high PRF, respectively, were compared through
their I-V characteristics and electrical stability under the gate bias voltage stress.
Finally, nc-Si:H TFT structure, produced and optimized in this work, was analyzed through
gate-insulator-drain/source capacitor by capacitance-voltage (C-V) measurements within
106-10-2 Hz frequency (F) range. The inversion regime was detected at low F without any
external charge injection. Besides, ac hopping conductivity in the nc-Si:H bulk was extracted
from the fitting results of the C-F curves.
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Growth And Characterization Of Cuin1-x Gaxse2 (cigs) Thin Films For Solar Cell StructuresCandan, Idris 01 December 2009 (has links) (PDF)
Direct conversion of solar energy, which is the most powerful and unlimited one among the renewable energy sources / into the electrical energy by the photovoltaic devices, is a promising way of meeting the energy needs of future. Thin film semiconductor materials show great promise for the production of efficient, low-cost solar cell devices. Recently advanced research on thin film photovoltaics in all aspects, has attracted intense attention. Thin film semiconductors for the photovoltaic applications are deposited in large areas by different methods.
In this study, deposition and characterization of CuIn1-x GaxSe2 ( CIGS ) semiconductor thin films by thermal evaporation and e-beam evaporation methods were investigated. Material properties and deposition parameters of the thin films are aimed to be optimized for solar cell applications. Structural properties of the deposited CIGS thin films were examined through X-ray diffraction and Energy Dispersive X-ray Analysis. The temperature dependent electrical conductivity, Hall effect and photoconductivity of these samples have been measured between 100 and 400 K. For the optical characterization of CIGS thin films, the transmission measurements have been carried out in the wavelength region of 325-900 nm. The changes in the structural, electrical and optical properties of samples through post-depositional annealing effect were also analyzed.
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1068 |
Nanocrystal Silicon Based Visible Light Emitting Pin DiodesAnutgan, Mustafa 01 December 2010 (has links) (PDF)
The production of low cost, large area display systems requires a light emitting material
compatible with the standard silicon (Si) based complementary metal oxide semiconductor
(CMOS) technology. The crystalline bulk Si is an indirect band semiconductor with very
poor optical properties. On the other hand, hydrogenated amorphous Si (a-Si:H) based wide
gap alloys exhibit strong visible photoluminescence (PL) at room temperature, owing to the
release of the momentum conservation law. Still, the electroluminescence (EL) intensity from
the diodes based on these alloys is weak due to the limitation of the current transport by the
localized states.
In the frame of this work, first, the luminescent properties of amorphous silicon nitride
(a-SiNx:H) thin films grown in a plasma enhanced chemical vapor deposition (PECVD) system
were analyzed with respect to the nitrogen content. Then, the doping effciency of p- and
n-type hydrogenated nanocrystalline Si (nc-Si:H) films was optimized via adjusting the deposition
conditions. Next, the junction quality of these doped layers was checked and further
improved in a homojunction pin diode.
Heterojunction pin light emitting diodes (LEDs) were fabricated with a-SiNx:H as the
luminescent active layer. The EL effciency of the fresh diodes was very low, as expected.
As a solution, the diodes were electro-formed under high electric field leading to nanocrystallization
accompanied by a strong visible light emission from the whole diode area. The
current-voltage (I-V) and EL properties of these transformed diodes were investigated in detail.
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1069 |
Near Infrared Interference Filter Design And The Production Withion-assisted Deposition TechniquesAydogdu, Selcuk 01 February 2012 (has links) (PDF)
Near infrared region (NIR) of the electromagnetic spectrum (EM) is defined as 700nm to
1400nm wavelength interval by International Commission on Illumination(CIE). This wavelength
interval is extensively used for target acquisition, night vision, wireless communication
etc. Therefore, filtering the desired portion of EM spectra becomes a need for that kind
of applications. Interference filters are multilayer optical devices which can be designed and
produced for the desired wavelength intervals. The production of near infrared interference
filters is a process of depositing thin material layers on the suitable substrates. In this thesis, a
multilayer NIR filter will be designed for a selected wavelength interval by the use of dierent
materials. Then, transmission quality, thermal stability, dependence of the transmission
values on the incoming beam angle, performance and durability of the filter will be studied.
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1070 |
Alkynylated acenothiadiazoles and N-heteroacenes: synthesis, functionalization, and study of the optical properties for optoelectronic and sensory materialsBrombosz, Scott M. 15 June 2010 (has links)
For organic electronic device applications materials are needed which display good charge carrier mobility, good processability, and stability towards oxygen and moisture. Alkynylated N-Heteroacenes fulfill many of these requirements. Substitution with alkyne groups as well as the introduction of the pyrazine subunit both inhibits oxidative degradation at sensitive position in the molecules. Additionally the trialkylsilylethynyl group aides in directing the packing motif as well as vastly increases the solubility over unsubstituted analogues.
A requisite precursor in the synthesis of alkynylated N-heteroacenes is alkynylated acenothiadiazoles. These thiadiazoles display interesting photophysical properties and can be functionalized to produce a wide range of properties in closely related materials. The acenothiadiazoles themselves have potential applications as an N-type semiconductor. Optical gaps and calculated HOMO-LUMO gaps show that these molecules, when compared to known N-type materials, should be easily injected with electrons. Additionally the crystal packing of these compounds shows favorable π-orbital overlap which should provide excellent charge carrier mobilities.
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