A radio‐frequency glow discharge is used to deposit films of amorphous silicon from silane gas on to substrates at 25°–650°C. These films have resistivities at 21°C of up to 1014 ohm‐cm and have large temperature coefficients of resistivity. A photoconductive effect is observed which reaches a maximum for films deposited at 300°C, and a sample is compared with a cell. The effects of heat‐treatment, ageing, and doping on the properties of amorphous silicon are reported. The variation of properties with deposition temperature is related to the structural changes with temperature that have been observed for this material.