Changes in band alignment during annealing at 600°C of ALD Al2O3 on (InxGa1-x)2O3 for x=0.25-0.74

Changes in valence band offsets (VBOs) as a result of annealing of heterostructures of atomic layer deposited Al2O3 on (InxGa1-x)(2)O-3 (where x=0.25-0.75), grown by pulsed laser deposition, are reported. The heterostructures have been annealed at 600 degrees C to simulate the expected thermal budget during device fabrication. The VBOs decrease significantly as a result of annealing, with the change being larger at higher indium concentrations. The decrease in VBO ranges from -0.38eV for (In0.25Ga0.75)(2)O-3 to -1.28eV for (In0.74Ga0.26)(2)O-3 and is likely due to increased interfacial disorder at the heterointerface as well as phase differences between gallium-rich samples and indium-rich samples. After annealing, the band alignment remains type I (nested gap) for x=0.25, 42, and 60 but becomes type II for the (In0.74Ga0.26)(2)O-3 sample.