On anomalous drift mobility results in α-silicon alloys

Standard carrier drift experiments using a nano second pulsed laser have been performed on near micron thick α-Si alloys sandwiched between blocking metal and injecting contacts. Our results show that the transient response is only partially due to the drifting carriers. Another major contribution comes from the previously neglected time-dependent relaxation of the Schottky barrier space charge layer after excitation. The accompanying current resembles a slow dispersive drift of carriers. Consequently, generally accepted estimates for the drift mobility which ignored this extra current may therefore be unreliable.