Investigation of energy band at atomic layer deposited AZO/β-Ga2O3 ($$ \overline{2}01 $$) heterojunctions

The Al-doped effects on the band offsets of ZnO/β-Ga2O3 interfaces are characterized by X-ray photoelectron spectroscopy and calculated by first-principle simulations. The conduction band offsets vary from 1.39 to 1.67 eV, the valence band offsets reduce from 0.06 to − 0.42 eV, exhibiting an almost linear dependence with respect to the Al doping ratio varying from 0 to 10%. Consequently, a type-I band alignment forms at the interface of ZnO/β-Ga2O3 heterojunction and the AZO/β-Ga2O3 interface has a type-II band alignment. This is because incorporating Al into the ZnO would open up the band gaps due to the strong Al and O electron mixing, and the conduction and valence band edges consequently shift toward the lower level.