Band alignment of AlN/<i>β-</i>Ga2O3 heterojunction interface measured by x-ray photoelectron spectroscopy

Abstract

The energy band alignment of AlN/β-Ga2O3 heterostructures was investigated by X-ray photoelectron spectroscopy. The valence band offsets were estimated to be −0.09 ± 0.1 eV (type II alignment) for AlN grown by plasma enhanced atomic layer deposition (PEALD) on β-Ga2O3 and 0.72 ± 0.1 eV (type I alignment) for AlN prepared by thermal atomic layer deposition (T-ALD) on β-Ga2O3, which gives the conduction band offsets of 1.39 ± 0.1 eV for PEALD AlN and 0.58 ± 0.1 eV for T-ALD AlN. The large difference in the band alignment for the AlN/β-Ga2O3 heterostructures is dominated by different levels of oxygen incorporation into the AlN films as a result of different deposition techniques. The determination of the band alignment of the AlN/β-Ga2O3 heterostructure has significant implications for the design of electronic and optical devices based on AlN/β-Ga2O3 heterojunctions.