AbstractThis is to study on the advantage of plasma‐less deposition in catalytic chemical vapour deposition (Cat‐CVD), often called hot‐wire CVD. The effects of plasma damage are particularly studied by the performance of amorphous‐silicon thin film transistors (a‐Si TFTs), since it is strongly affected by the property of an interface between a gate insulating film and an a‐Si film. It is found that the plasma damage at the interface affects on off‐current of TFT, and that the off‐current of Cat‐CVD a‐Si TFT is much lower than that of a‐Si TFT in which all films are prepared by the conventional plasma‐enhanced CVD (PECVD). The off‐current of Cat‐CVD a‐Si TFTs is likely to increase and approach to the same level as the off‐current of PECVD a‐Si TFT, when Cat‐CVD a‐Si is exposed to weak plasma. In addition, since the off‐current is so low, when the ratio of the channel width (W) to the channel length (L) is adjusted, the on‐current can be increased up to the same level as the on‐current of poly‐crystalline silicon (poly‐Si) TFT with keeping the off‐current on the same level as that of poly‐Si one. That is, it is concluded that a‐Si TFT with current drivability equivalent to poly‐Si TFT can be produced by using plasma‐less Cat‐CVD method for preparing films used in TFTs. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)