High-mobility thin-film transistor fabricated using hydrogenated amorphous silicon deposited by discharge of disilane

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 cm(3)/min to 1.5 cm(3)/min, the maximum field-effect electron mobility (mu(FE)) of the TFT which depends on the gate voltage increased from 3.3 cm(2)/(V . s) to 4.9 cm(2)/(V . s), accompanied by a reduction in the silicon-hydrogen bond content. There was a negative correlation between mu(FE) and the silicon-hydrogen bond content in the a-Si:H film. The improvement mechanism of mu(FE) was discussed in terms of the chemical structure of the a-Si:H film.