High-Mobility Thin-Film Transistor Fabricated Using Hydrogenated Amorphous Silicon Deposited by Discharge of Disilane

Abstract
Plasma-enhanced chemical vapor deposition of hydrogenated amorphous silicon (a-Si:H) film was investigated with emphasis on the effect of disilane flow rate. A coplanar thin-film transistor (TFT) was fabricated using this a-Si:H film. Silicon-hydrogen bond content in the a-Si:H film was measured by infrared absorption spectroscopy. With decrease in the disilane flow rate from 3.0 cm3/min to 1.5 cm3/min, the maximum field-effect electron mobility (µ FE) of the TFT which depends on the gate voltage increased from 3.3 cm2/( V·s) to 4.9 cm2/( V·s), accompanied by a reduction in the silicon-hydrogen bond content. There was a negative correlation between µ FE and the silicon-hydrogen bond content in the a-Si:H film. The improvement mechanism of µ FE was discussed in terms of the chemical structure of the a-Si:H film.

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