Browsing by Author "LIN, CW"

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AMBIPOLAR PERFORMANCES OF NOVEL AMORPHOUS SILICON-GERMANIUM ALLOY THIN-FILM TRANSISTORS
(1993-08-01)
HSIEH, SW
;
CHANG, CY
;
LEE, YS
;
LIN, CW
;
WU, BS
The limitation of low hole mobility in hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs) was overcome in this present work by utilizing hydrogenated amorphous silicon-germanium (a-Si1-xGex:H) alloys as the active channel of TFTs. The performance of hydrogenated amorphous silicon-germanium thin film transistors (a-SiGe:H TFTs) was optimized by switching the germane-to-silane flow ratio. The fabricated a-SiGe:H TFT with 12 at% germanium content was measured as possessing an electron mobility of 0.71 cm2/V.s and a hole mobility of 0.54 cm2/V.s. The on/off current ratio ranging over almost six orders of magnitude in both conduction modes was obtained. Thus a-SiGe:H TFT has offered the opportunity for upgrading of a-Si:H TFTs and would be feasible for application in [CMOS] circuits.
PROPERTIES OF PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITED A-SINX-H BY VARIOUS DILUTION GASES
(1994-09-15)
HSIEH, SW
;
CHANG, CY
;
LEE, YS
;
LIN, CW
;
HSU, SC
The effects of dilution gases on hydrogenated amorphous silicon nitride (a-SiNx:H) films were investigated. Silane and ammonia were used as the reactive species, while nitrogen, helium, hydrogen, and argon were used as the-dilution gases in a plasma-enhanced chemical vapor-deposition system at a substrate temperature of 300 degrees C. The electrical, physical, and chemical properties of the a-SiNx:H films were found to be highly sensitive to the various kinds and flow rates of the carrier gases in the deposition. Additionally, the physical properties of growth rate, refractive index, and etching rate were also investigated. The hydrogen bonding configuration was explored by infrared spectroscopy. The total hydrogen concentrations for all a-SiNx:H films were observed to be smaller than 3.0X 10(22) cm-(3). The electrical properties were characterized by I-V and C-V measurements in metal-insulator-semiconductor structures. The breakdown strength was determined at the current density of 3 mA/cm(2); in addition, the dominant mode of electronic conduction would appear to be the Poole-Frenkel emission. The interface trap state density D-it which ranged from 3.4X10(11) to 1.3X10(12) cm(-2) eV(-1) was evaluated by the C-V characteristics. Finally, the influences of the gas dilution in the alpha-SiNx:H films, as applied to the devices, were investigated by using the hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs). Analyses of the transfer characteristics of the TFT devices revealed that the density of deep gap states is 4x10(12) cm(-2) eV(-1) and the field-effect mobility mu(FE) is changing from 0.37 to 1.45 cm(2)/V s.