TUNNELING MEASUREMENTS OF SYMMETRICAL-INTERFACE PHONONS IN GAAS ALAS DOUBLE-BARRIER STRUCTURES/

In this paper we report the results of extensive magnetotransport expe riments on asymmetric GaAs/AlAs double-barrier structures that were sp ecifically designed to possess large phonon-assisted tunneling current s. We find quantitative agreement between measured valley currents at liquid-helium temperature and calculations that include the effects of phonon localization using the dielectric-continuum model. The results demonstrate that (1) a major part of the valley current in these stru ctures is due to phonon-assisted tunneling, and (2) symmetric-interfac e phonons and confined phonons in the GaAs well are the most important in phonon-assisted tunneling processes. Charge buildup in the GaAs we ll is found to shift current-voltage curves to higher voltages and to distort magnetic field versus applied voltage diagrams.