Characterization of pseudomorphic γ-Ga2O3 and γ-Al2O3 films on MgAl2O4 substrates and the band-alignment at the coherent γ-Ga2O3/Al2O3 heterojunction interface

Abstract

We characterized 3.0 nm γ-Ga2O3, 3.0 nm γ-Al2O3, and 1.0/3.0 nm γ-Ga2O3/Al2O3 films grown on (100) MgAl2O4 substrates. X-ray diffraction measurements revealed that γ-Ga2O3 and γ-Al2O3 films were coherent to the substrate with Poisson's ratios of 0.31 and 0.28. While, X-ray photoelectron spectroscopy found that band gaps of the γ-Ga2O3 and γ-Al2O3 films were 5.6 and 7.4 eV, respectively, and that the γ-Ga2O3/Al2O3 heterojunction had type-I band alignment with conduction- A nd valence-band-offsets of 1.6 and 0.2 eV, respectively. These findings regarding the end members of γ-(AlxGa1-x)2O3 will be beneficial for further study on γ-(AlxGa1-x)2O3-based heterostructures.