Interaction of defects with solar irradiation for devices used ZnO/Ga2O3 heterojunctions in which Ga2O3 prepared using oxidation of the heavily doped p-type GaAs

The effect of the growth condition on the interaction of defects with solar irradiation for devices that use ZnO/Ga2O3 heterojunctions is studied. A Ga2O3 layer was grown on the heavily doped p-type GaAs wafer using a dry oxidation process. The surface of the Ga2O3 film grown with a low O2/N2 gas ratio is very flat, whereas there is a large number of cracks on the surface of the Ga2O3 film grown with a high O2/N2 gas ratio. This is because of the sensitivity of oxidation, nucleation and crystallization to an oxygen annealing ambient. Because of the strong visible-emission absorption for ZnO and Ga2O3 films, the devices that use ZnO/Ga2O3 heterojunctions exhibit the response properties to solar irradiation and photovoltaic behavior. An oxygen vacancy- (VO-), gallium vacancy- (VGa-) and VO-VGa complex-related band model is proposed to describe the transition processes for the photo-generation of carriers and the contribution to the photocurrent.