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

We characterized 3.0 nm gamma-Ga2O3, 3.0 nm gamma-Al2O3, and 1.0/3.0 nm gamma-Ga2O3/Al2O3 films grown on (100) MgAl2O4 substrates. X-ray diffraction measurements revealed that gamma-Ga2O3 and gamma-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 gamma-Ga2O3 and gamma-Al2O3 films were 5.6 and 7.4 eV, respectively, and that the gamma-Ga2O3/Al2O3 heterojunction had type-I band alignment with conduction-and valence-band-offsets of 1.6 and 0.2 eV, respectively. These findings regarding the end members of gamma-(AlxGa1-x)(2)O-3 will be beneficial for further study on gamma-(AlxGa1-x)(2)O-3-based heterostructures. (C) 2019 The Japan Society of Applied Physics