Ion implantation of phosphorus was used to dope amorphous and microcrystalline silicon with the aim of achieving a low-temperature, self-aligned process for forming n(+) contacts to top-gate thin-film transistors. Amorphous and microcrystalline films made with both RF glow discharge and hot-wire chemical vapor deposition were implanted. The effect of the dose, energy and implantation temperature and subsequent annealing at increasing temperatures on the dark conductivity, activation energy and photoconductivity were studied. Lowering the energy (15 keV) while increasing the dose (10(15) cm(-2)) and the implantation temperature (300 degrees C) resulted in the highest after anneal (300 degrees C) dark conductivity for both hot-wire (0.3 Ohm(-1)cm(-1)) and RF (0.2 Ohm(-1) cm(-l)) microcrystalline films.