Browsing by Author "Wang, M. C."

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Analysis of parasitic resistance and channel sheet conductance of a-Si : H TFT under mechanical bending
(2007)
Wang, M. C.
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Chang, T. C.
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Liu, Po-Tsun
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Tsao, S. W.
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Chen, J. R.
The effect of mechanical strain on the performance of a-Si: H thin-film transistors (TFTs) with different channel lengths was studied under uniaxial compressive and tensile strain applied parallel to the TFT source-drain current path. The source-drain parasitic resistance and channel sheet conductance were extracted to explain the device performance under mechanical strain. These results indicate that the compressive bending leads to a significant decrease (similar to 16%) in the source-drain parasitic resistance. The channel sheet conductance has shown a 6% variation under mechanical bending. The variation under mechanical bending strain originates from the evolution of defect state density in a-Si:H channel material. (c) 2007 The Electrochemical Society.
Cu/CuMg gate electrode for the application of hydrogenated amorphous silicon thin-film transistors
(2007)
Wang, M. C.
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Chang, T.-C.
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Liu, Po-Tsun
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Li, Y. Y.
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Xiao, R. W.
The feasibility of using Cu/CuMg as a gate electrode for a-Si:H thin-film transistors (TFTs) has been investigated in this work. The issue of adhesion between the Cu film and glass substrates has been overcome by introducing the Cu/CuMg alloy. Furthermore, a wet-etching process of Cu-based gate metal has been proposed by using the copper etchant in the conventional printed circuit boards. The experimental result showed superior performance of a-Si:H TFT with desired electrode taper angle and minimal loss of critical dimension. The a-Si:H TFT exhibited mobility of 0.37 cm(2)/V s, subthreshold slope of 0.83 V/dec, and V(th) of 2.02 V.
Mechanical bending effect on the photo leakage currents characteristic of amorphous silicon thin film transistors
(2010-11-01)
Wang, M. C.
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Tsao, S. W.
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Chang, T. C.
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Lin, Y. P.
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Liu, Po-Tsun
The photo leakage current (I(PLC)) characteristic of a-Si:H TFTs under different bending strains has been studied. The larger I(PLC) of a-Si:H TFTs under the outward bending strain is due to larger conductivity of a-Si:H, stemmed from the shift up of Fermi level (E(F)). Experimental results show the I(PLC) of a-Si:H TFTs under the outward bending strain is larger than that of flattened and inward bending a-Si:H TFTs in the density of states (DOS) limited region, stemmed from the lower recombination centers present in outward bending a-Si:H material. Furthermore, the extracted smaller activity energy (E(a)) of a-Si:H TFTs under the outward bending strain also confirmed the shift of E(F). (C) 2010 Elsevier Ltd. All rights reserved.
Mechanical bending effect on the photo leakage currents characteristic of amorphous silicon thin film transistors
(2010-11-01)
Wang, M. C.
;
Tsao, S. W.
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Chang, T. C.
;
Lin, Y. P.
;
Liu, Po-Tsun
The photo leakage current (I(PLC)) characteristic of a-Si:H TFTs under different bending strains has been studied. The larger I(PLC) of a-Si:H TFTs under the outward bending strain is due to larger conductivity of a-Si:H, stemmed from the shift up of Fermi level (E(F)). Experimental results show the I(PLC) of a-Si:H TFTs under the outward bending strain is larger than that of flattened and inward bending a-Si:H TFTs in the density of states (DOS) limited region, stemmed from the lower recombination centers present in outward bending a-Si:H material. Furthermore, the extracted smaller activity energy (E(a)) of a-Si:H TFTs under the outward bending strain also confirmed the shift of E(F). (C) 2010 Elsevier Ltd. All rights reserved.
n(+)-doped-layer-free microcrystalline silicon thin film transistors fabricated with the CuMg as source/drain metal
(2007-07-09)
Wang, M. C.
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Chang, T. C.
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Liu, Po-Tsun
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Xiao, R. W.
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Lin, L. F.
The feasibility of using CuMg as source/drain metal electrodes for n(+)-doped-layer-free microcrystalline silicon thin film transistors (mu-Si:H TFTs) has been investigated. The Ohmic-contact characteristic has been achieved by using the CuMg alloy as source/drain metal. Furthermore, a wet etching process of Cu alloy source/drain metal has been completed by using the ferric chloride base etchant. The proposed mu-Si:H TFT has shown similar electrical characteristic with the mu-Si:H TFT with n(+)-doped layer. The experimental result also showed that the CuMg alloy was suitable for the replacement of n(+)-doped layer in thin film transistor liquid-crystal displays. (C) 2007 American Institute of Physics.
Photo-leakage-current characteristic of F incorporated hydrogenated amorphous silicon thin film transistor
(2007-05-07)
Wang, M. C.
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Chang, T. C.
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Liu, Po-Tsun
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Tsao, S. W.
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Chen, J. R.
The photo-leakage-current (I-PLC) characteristic of F incorporated a-Si:H thin film transistor (TFT) has been studied. The device activation energy (E-a) of a-Si:H(:F) TFTs is higher than those of typical a-Si:H TFTs, and resulted in the shift down of Fermi level in a-Si:H(:F). Experimental results show that the I-PLC of a-Si:H(:F) TFTs is smaller than that of conventional a-Si:H TFTs in the density of states limited region, stemmed from the higher recombination centers present in a-Si:H(:F) material. However, the higher I-PLC is observed in the hole conduction region, resulted from the larger E-a in the a-Si:H(:F) TFTs. (C) 2007 American Institute of Physics.
Schottky barrier height for the photo leakage current transformation of a-Si : H TFTs
(2007)
Wang, M. C.
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Chang, T. C.
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Liu, Po-Tsun
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Li, Y. Y.
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Xiao, R. W.
For effectively reducing the off-state signal loss resulting from the a-Si: H thin film transistors' (TFTs) photo leakage current, the a-Si: H TFTs with the use of indium tin oxide as source-drain metal have been fabricated for this study. A remarkable transformation in photo leakage current has been observed under the 3300 cd/m(2) cold cathode fluorescent lamp (CCFL) backlight illumination. The source-drain barrier height engineering has been proposed for this study. According to the energy band diagram, the barrier height for hole is estimated to be about 3 eV. As a result, the photogeneration holes blocked in the Schottky barrier could effectively result in the different characteristic of photo leakage current. (c) 2007 The Electrochemical Society.
Source-drain barrier height engineering for suppressing the a-Si : H TFTs photo leakage current
(2007-12-03)
Wang, M. C.
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Chang, T. C.
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Liu, P. T.
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Li, Y. Y.
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Huang, F. S.
For effectively reducing the off-state signal loss resulted from the a-Si:H TFTs photo leakage current, the a-Si:H TFTs with the use of ITO as source-drain metal have been fabricated for this study. Several TFT structures have been fabricated to examine this characteristic. A remarkable reduction in photo leakage current has been observed under the 3300 cd/m(2) CCFL backlight illumination. The source-drain barrier height engineering has been proposed for these results. According to the energy band diagram, the barrier height for hole is estimated about 3 eV. As a result, the photo-generation holes blocked in the source-drain barrier height could effectively reduce the photo leakage current in off-state. (C) 2007 Elsevier B.V. All rights reserved.
Suppression of Schottky leakage current in island-in amorphous silicon thin film transistors with the Cu/CuMg as source/drain metal
(2007-08-06)
Wang, M. C.
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Chang, T. C.
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Liu, Po-Tsun
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Xiao, R. W.
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Lin, L. F.
The feasibility of using Cu/CuMg as a source/drain metal for the island-in amorphous silicon thin film transistors (a-Si:H TFTs) has been investigated. The issue of adhesion between the Cu film and n(+)-a-Si layer has been overcome by introducing the Cu/CuMg alloy. Furthermore, the suppression of Schottky leakage current in metal/a-Si:H structure was also observed in the island-in a-Si:H TFT. The island-in a-Si:H TFT exhibited the mobility of 0.52 cm(2)/V s, the subthreshold slope of 0.78 V/decade, and the V-th of 3.02 V. The experimental result also showed superior performance of the a-Si:H TFT with minimal loss of critical dimension and good thermal stability.
The instability of a-Si : H TFT under mechanical strain with high frequency ac bias stress
(2007)
Wang, M. C.
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Chang, T. C.
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Liu, Po-Tsun
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Tsao, S. W.
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Lin, Y. P.
The instability of amorphous Si thin film transistors under uniaxial strain has been studied. Compared to the effect of tensile bias stress, larger threshold voltage shift is observed under compressive bias stress. These results are related to the damage of weak Si-Si bonds during the ac bias stress. However, the V-th shift of devices on the re-flattened substrate is larger after tensile strain than that of compressive strain. In addition, the defeat diminished effect of tensile situation is decreased after re-flattening the device. Therefore, after re-flattening the substrate the Vth shift resulting from tensile bias stress is larger than that of the compressive one. (c) 2007 The Electrochemical Society.