Browsing by Author "HSIEH, SW"

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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.
CHARACTERISTICS OF LOW-TEMPERATURE AND LOW-ENERGY PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITED SIO2
(1993-08-15)
HSIEH, SW
;
CHANG, CY
;
HSU, SC
;
電子物理學系
;
電控工程研究所
Deposition of high quality silicon dioxides was obtained at low temperatures by a specially designed plasma chemical vapor deposition (PECVD) system. The system employed a long quartz tube as a reactor and a set of three vertically standing plates for glow discharge. The deposited oxide, which employed a large amount of helium (He) to dilute silane (SiH4) and nitrous oxide (N2O) reactants, was observed to possess excellent qualities, as compared to those of thermally grown oxides. The chemical composition used for obtaining electrical integrities of the PECVD oxides was investigated. Additionally, the effects of post-metallization annealing on the oxides were investigated in detail. Oxides deposited at a substrate temperature of 250-degrees-C were observed to possess a low interface trap state density (D(it)) of only 3 X 10(10) cm-2 eV-1 and low total trapped charge density (Q(total)) of 5.8 X 10(16) cm-3. Those, however, which were deposited at 350-degrees-C, have more stable electrical characteristics under current/voltage bias-temperature stress, but their D(it) and Q(total) are around 2 X 10(11) cm-2 eV-1 and 3.4 X 10(16) cm-3, respectively. An atom-bonding model was proposed in this present work, according to physical, chemical, and electrical analyses in accounting for phenomena of charge-trapping and also in upgrading the electrical integrity of the deposited oxides. The applicability of these low-temperature oxides toward fabricating hydrogenated amorphous-silicon thin film transistor (a-Si:H TFT's) was investigated. Adequate electrical performances of the TFT's with a high on/off current ratio of more than 10(6) and high field effect mobility (mu(FET)) Of around 0.6 cm2/V s were obtained.
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.