Abstract

We report the first investigation of high-field transport in GaAs with 20-fs time resolution by direct detection of the emitted THz radiation using ultrabroadband electrooptic sampling techniques. This should be contrasted with earlier studies in which the time resolution was limited to 500 fs¹ and measurements using an indirect pump-probe technique with a response in the 10-fs regime.² The uitrafast time resolution allows us to directly probe the initial transport dynamics, and provides information about ballistic acceleration, maximum velocity overshoot, and intervalley transfer as a function of electric field. A knowledge of these nonequilibrium transport properties would be extremely useful for the modeling of the next generation of ultrahigh speed devices.

© 1998 Optical Society of America