Preparation of silicon-carbon alloy films by hot-wire CVD and their properties

The capability of hot-wire chemical vapor deposition (HWCVD, Cat-CVD) has b een studied for the preparation of silicon-carbon alloy (Si1-xCx) films. Th e changes in deposition rate, carbon content, optical gap and IR absorption of Si-C and C-H-n are demonstrated for Si1-xCx alloy films deposited with the preparation conditions, gas ratio R=CH4/(SiH4+CH4+H-2) from 0.3 to 0.6, and filament temperature from 1750 to 2100 degreesC. A deposition rate ove r 0.9 nm/s is obtained for all samples. The samples have a heterogeneous st ructure, consisting of hydrogenated amorphous silicon-carbon alloy (a-Si1-y Cy:H) and hydrogenated microcrystalline silicon ( Lc-Si:H). Impurity doping using B,H, gas has been tried for the sample with a carbon content of simi lar to 28%. The photoconductivity was measured, and the activation energy f or the dark conductivity was 0.17 eV with the doping gas ratio, B2H6/(SiH4CH4) of similar to0.054%. (C) 2001 Elsevier Science B.V. All rights reserve d.