HOT-ELECTRON SPECTROSCOPY OF UNDOPED GAAS GAALAS SUPERLATTICES/

We present direct evidence of ballistic electrons traversing nominally undoped GaAs/GaAlAs short period superlattices with different well wi dths. The measurements are carried out using a hot-electron transistor as an electron spectrometer. An energy tunable electron beam is injec ted via a tunneling barrier into the field free superlattice and the t ransmitted collector current is measured as a function of the injector energy. Significant increase of the collector current is observed due to miniband conduction in the superlattice. The transfer characterist ics shows excellent agreement with the calculated positions of the min ibands and minigaps. Longitudinal optical (LO) phonon replicas of the eigenstate structure are present. (C) 1997 Academic Press Limited.