The effect of oxygen annealing on characteristics of β-Ga2O3 solar-blind photodetectors on SiC substrate by ion-cutting process

Abstract

In this work, a high quality (2̅01) β-Ga2O3 single-crystalline film was transferred to the 4H-SiC substrate by ion-cutting technique, on which the metal-semiconductor-metal (MSM) solar-blind photodetectors (PDs) were fabricated. The effect of the oxygen annealing on the performance of PDs has been systematically studied. The PD fabricated on the as-transferred film exhibits a high responsivity (R) of 2.24 A/W with a large external quantum efficiency of 1.21 × 103%, and an ultrahigh responsivity rejection ratio (R240nm/R350nm) of 1.02 × 105. In comparison, the PD based on the β-Ga2O3 film annealed in oxygen atmosphere exhibits a reduced dark current of 0.6 nA at the bias of 5 V, a fast decay time of 41 ms but a relatively reduced internal gain. It is resulted from the increased Schottky barrier height and the suppression of persistent photoconductivity effect due to the reduced density of surface oxygen vacancies and defects upon annealing. These results would promote a better understanding of dark current and responsivity of PDs modulated by oxygen annealing.