In the search for a material with electrical properties similar to those of amorphous silicon or amorphous silicon germanium, but stable under light soaking, hydrogenated microcrystalline silicon–carbon alloy (µc-Si 1− x C x: H) thin films are a promising candidate. The interest in these materials lies in the possibility of varying the effective band gap by changing the amount of carbon in the alloy composition, while keeping a high crystalline fraction to maintain stability under light-soaking. In this study, µc-Si 1− x C x: H thin films were deposited by radio frequency (RF) plasma enhanced chemical vapour deposition using a silane and methane gas mixture highly diluted in hydrogen. Three deposition parameters were investigated as a means to control the film crystallinity: the RF power density, the methane flow rate and the presence of a small amount of silicon tetrafluoride …