Band-offset non-commutativity of GaAs/AlGaAs interfaces probed by internal photoemission spectroscopy

Abstract

The GaAs/AlGaAs material system is believed to have a band offset without remarkable influence from the interface. We report here probing a slightly higher (5-10 meV) valence-band offset at the GaAs-on-Al0.57Ga0.43As interface compared to that of the Al0.57Ga0.43As-on-GaAs interface, by using internal photoemission spectroscopy. This indicates the non-commutativity of band offset for GaAs/AlGaAs, i.e., the dependence on the order of the growth of the layers. This result is consistently confirmed by observations at various experimental conditions including different applied biases and temperatures.