Abstract

The dynamics of hot photoexcited or injected carriers in semiconductors has been studied extensively with picosecond and femtosecond optical pulses[1]. On a subpicosecond time scale, both absorption saturation[2] and photoluminescence techniques[3] were employed to trace the relaxation of the initial nonequilibrium distribution of carriers after their injection. These techniques have in common, that they probe the carrier distribution in the bands, but not the actual time dependent transport properties like mobility or drift velocity. These in turn are the important parameters for high speed devices like hot electron transistors. On the other hand, electron transport in semiconductors has been investigated by microwave conductivity measurements and microwave time-of-flight techniques. However, the time resolution of the existing microwave sources is not high enough to observe transient transport phenomena on a picosecond or even femtosecond time scale.

© 1987 Optical Society of America