Browsing by Author "Liang, CW"

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Characterization of anodic aluminum oxide film and its application to amorphous silicon thin film transistors
(1996-02-01)
Liang, CW
;
Luo, TC
;
Feng, MS
;
Cheng, HC
;
Su, D
AL(2)O(3)/SINx double-layered dielectric films suitable for large-size amorphous silicon thin film transistor liquid crystal displays (a-Si:H TFT LCD) have been prepared by anodization and plasma enhanced chemical vapor deposition (PECVD). Al2O3 films were formed at various pH values and volume ratio of water (H2O%) in the electrolyte. The optimal quality of Al2O3 film was achieved at pH = 6 and H2O% = 30. These high-quality Al2O3 films have denser structure, lower etching rate (90 Angstrom min(-1)) and smooth surface morphology after etching. The capacitors made of the anodization show a breakdown field as high as 7.8 MV cm(-1) and a low leakage current density of 10 nA cm(-2) at a dielectric field of 3 MV cm(-1). Furthermore, a-Si:H TFTs with Al gate and different gate dielectrics (Al2O3/SINx and SiNx) were also fabricated and evaluated. The TFTs with Al2O3/SiNx double-layered gate dielectric provide better performances, such as the smaller threshold voltage (1.76 V), improved subthreshold swing (1.0 V dec(-1)), and lower off-current (3.8 PA) than those of the device with single SiNx, film.
Microcrystallinity of undoped amorphous silicon films and its effects on the transfer characteristics of thin film transistors
(1995-01-01)
Liang, CW
;
Chiang, WC
;
Feng, MS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Microcrystallinity of undoped amorphous silicon films and its effects on the transfer characteristics of thin-film transistors
(1995-11-01)
Liang, CW
;
Chiang, WC
;
Feng, MS
;
材料科學與工程學系
;
電控工程研究所
The microcrystallinity of hydrogenated amorphous silicon films deposited by the conventional radio-frequency plasma-enhanced chemical vapor deposition (rf-PECVD) method and its dependence on chamber pressure are discussed. In a wide range of pressure at which the microcrystalline film can be formed, a critical pressure (500 mT) is found. Films deposited at this critical pressure possess the highest crystalline volume fraction and the smallest grain size. An ion-bombardment-assisted model is proposed to explain the experimental results. Concerning the applications of microcrystalline films to thin-film transistors (TFTs), the subthreshold swing and the field effect mobility are studied, both of which are found to be smaller than those of the hydrogenated amorphous silicon (a-Si:H) TFTs.