Observation of subbands in the GaAlAs on two-dimensional electron gas field-effect transistor structures

Abstract
We have measured the current-voltage characteristics and its derivatives on GaAs-GaAlAs field-effect transistor samples having a semitransparent Au-Schottky gate contact, varying the band structure by illumination. In these samples electrons tunnel from the two-dimensional electron gas through the GaAlAs into a Schottky gate. Sharp peaks are observed in dI/dV after illumination at liquid-helium temperature. Using a self-consistent model, we are able to explain these peaks by resonant tunneling via subband states in the GaAlAs.