BALLISTIC ELECTRON-SPECTROSCOPY OF VERTICAL SUPERLATTICE MINIBANDS

We present a study of ballistic electron transport in GaAs/GaAlAs supe rlattices 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 collec tor current is observed due to miniband conduction in the superlattice . The transfer ratio alpha=I-C/I-E can be used to probe miniband posit ions and the miniband widths in field free superlattices. Longitudinal optical phonon replicas of the eigenstate structure are presented. Th e tunneling spectroscopy data agree well with self-consistent Poisson- Schrodinger calculations. (C) 1997 American Institute of Physics.