Dynamics of extreme nonequilibrium electron transport in GaAs

Hot electron effects have been observed in semiconductors for many decades; however, until recently, direct experimentally determined spectroscopic information on the hot electron distribution function did not exist. As a result the microscopic basis for hot electron transport could only be inferred. To bridge the gap between theory and experiment we invented hot electron spectroscopy, a technique which enabled us to obtain direct spectroscopic information on the electron momentum distribution, n(p) . In this paper we describe the technique and discuss hot electron spectra obtained in GaAs. "Ballistic" electron transport is observed in samples having narrow transit regions (1700 Å). In addition, a theoretical model has been developed enabling us to identify all observed features in the spectra.