Band offsets at interfaces of (100)InxGa1−xAs (0⩽x⩽0.53) with Al2O3 and HfO2

Abstract

The electron energy band alignment at interfaces of InxGa1-xAs (0 <= x <= 0.53) with atomic-layer deposited insulators Al2O3 and HfO2 is characterized using combined measurements of internal photoemission of electrons and photoconductivity. The measured energy of the InxGa1-x As valence band top is found to be only marginally influenced by the semiconductor composition. This result suggests that the observed band-gap narrowing from 1.42 to 0.75 eV when the In content increases from 0 to 0.53 occurs mostly through downshift of the semiconductor conduction band bottom. Electron states originating from the interfacial oxidation of InxGa1-xAs lead to reduction of the electron barrier at the semiconductor/oxide interface. (C) 2009 Elsevier B.V. All rights reserved,