We prepared hydrogenated amorphous silicon carbide thin films using SiH4, CH4 and H-2 gases by the hot-wire chemical vapor deposition method and investigated the influence of hydrogen gas flow rate, F(H-2), Oil their film properties. For F(H-2) between 10 and 100 seem, two groups of films were obtained: high E-g opt. (group H) and low E-g opt. (group L). The E-g opt in group H decreased from 2.27 to 2.14 eV when F(H-2) increased from 10 to 100 seem, and the E-g opt. in group L decreased from 1.93 to 1.78 eV when F(H-2) increased from 50 to 100 seem. The difference in E-g opt. between the two groups resulted from differences in the electrical power applied to the W wire and deposition on the W wire. (c) 2005 Elsevier B.V All rights reserved.