Ballistic electron spectroscopy of vertical superlattice minibands

Abstract

We present a study of ballistic electron transport in GaAs/GaAlAs superlattices with different well widths. A three terminal device is used to inject an energy tunable electron beam via a tunneling barrier into a field free superlattice and to collect the transmitted current as a function of the injector energy. A significant increase of the collector current is observed due to miniband conduction in the superlattice. The transfer ratio α=IC/IE can be used to probe miniband positions and the miniband widths in field free superlattices. Longitudinal optical phonon replicas of the eigenstate structure are presented. The tunneling spectroscopy data agree well with self-consistent Poisson–Schrödinger calculations.