Al2O3/β-Ga2O3(-201) Interface Improvement Through Piranha Pretreatment and Postdeposition Annealing

In this letter, we report on the improvement of atomic layer deposited (ALD) Al2O3/beta-Ga2O3 (-201) interface quality through piranha pretreatment and postdeposition annealing (PDA). The high quality interface is verified via the temperature dependent capacitance-voltage (C-V) and photo-assisted (deep UV) C-V measurements, considering its ultra wide bandgap of 4.8 eV for beta-Ga2O3. A low C-V hysteresis of 0.1 V from the measurement frequency of 1 kHz to 1 MHz is obtained, compared with the hysteresis of 0.45 V without piranha optimization. An average interface trap density (D-it) of 2.3 x 10(11) cm(-2) . eV(-1) is extracted from the photo C-V measurements. Piranha pretreatments and PDA turn out to be an effective way to improve the ALD Al2O3/beta-Ga2O3 (-201) interface for future high quality Ga2O3 metal-oxide-semiconductor field-effect transistors.