Si1-xCx films (SiC) are synthesized by methane/acetylene plasma immersion ion implantation (PIII) into silicon using self-ignited glow discharge and their properties are investigated. The synthesized SiC films have similar elemental composition (ratio) as that of the methane and acetylene precursors, except that the hydrogen content is higher for the films fabricated using methane. The films undergo a transformation from a-Si1-xCx:H to a multi-phase structure with increasing annealing temperature. The amount of Si-C bonds increases with annealing temperature whereas that of the C-C bonds changes in an opposite manner. At high annealing temperature, graphitization takes place in the carbon clusters in the films but the extent is limited. At 1300 degreesC, the C-C bonds almost disappear completely. (C) 2003 Elsevier B.V. All rights reserved.