DRIFT MOBILITY OF ELECTRONS IN PHOSPHORUS-DOPED A-SIH

A study has been made of how doping and prolonged illumination affect the electron drift mobilitY mu(d) in a-Si:H over the temperature range 100-400 K. The curves Of mu(d)(T) found are activation-law curves at low temperatures. Saturation sets in near room temperature. The value of mu(d) near room temperature varies in a nonmonotonic way with the d oping, increasing at low doping levels and decreasing at high levels. The activation-law nature of the mu(d)(T) curves at low temperatures i s explained on the basis of a model of an effective trapping level. It is suggested that the saturation on the mu(d)(T) curves results from an increase in the effect of deep trapping levels with increasing temp erature.