Effect of Annealing on the Band Alignment of ALD SiO2 on (AlxGa1-x)2O3 for x = 0.2 - 0.65

Heterostructures of Atomic Layer Deposited SiO2 on thin layers of (AlxGa1-x)(2)O-3 with x = 0.2 - 0.65 deposited by Pulsed Laser Deposition were annealed at 600 degrees C to simulate ohmic contact formation in MOS devices. The valence band offsets decrease significantly as a result of this annealing, with the change dependent on the initial Al composition. The decrease ranges from 0.65 eV for (Al0.20Ga0.80)(2)O-3 to 1.75 eV for (Al0.65Ga0.35)(2)O-3 and is likely due to an increase in interfacial disorder as a result of annealing. Concurrently, the conduction band offsets increase, improving carrier confinement for electrons within the heterostructure. The band alignment remains type I (nested gap) across the entire composition range examined. (C) 2019 The Electrochemical Society.