Hole-Trapping Process at Al₂O₃/GaN Interface Formed by Atomic Layer Deposition

The hysteresis of the capacitance-voltage (C-V) characteristics of an Al₂O₃/n-GaN metal-insulator-semiconductor structure was evaluated under light (white LED)-irradiation and dark conditions. The hysteresis was not observed under the dark condition but was observed under the light-irradiation condition. The GaN surface was completely depleted in negative bias under the dark condition. The C-V characteristics indicated that the hysteresis is caused by hole trapping under the LED irradiation condition and that the holes are generated in the n-GaN surface by LED irradiation and subsequently injected into the Al₂O₃ films. When the holes are generated in the depletion region of GaN for any reason, such as a short generation lifetime, they can be trapped in the Al₂O₃ films.