Al2O3/ $\beta $ -Ga2O3(-201) Interface Improvement Through Piranha Pretreatment and Postdeposition Annealing

Abstract

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 $({\mathrm{ D}}_{\mathrm {it}})$ of $2.3 \times 10^{11}$ cm $^{\mathrm {-2}}\cdot $ eV $^{\mathrm {-1}}$ 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.