Energy barriers at interfaces between (100) In_xGa _1-xAs (0≤x≤0.53) and atomic-layer deposited Al ₂O₃ and HfO₂

The electron energy band alignment at interfaces of Inx Ga1-x As (0≤x≤0.53) with atomic-layer deposited insulators Al2 O3 and HfO2 is characterized using internal photoemission and photoconductivity experiments. The energy of the Inx Ga1-x As valence band top is found to be only marginally influenced by the semiconductor composition. This result suggests that the known bandgap 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. It finds support from both electron and hole photoemission data. Similarly to the GaAs case, electron states originating from the interfacial oxidation of Inx Ga1-x As lead to reduction in the electron barrier at the semiconductor/oxide interface.