X-ray Detection Performance of Vertical Schottky Photodiodes Based on a Bulk β-Ga₂O₃ Substrate Grown by an EFG Method

Abstract

In this study, we investigated the X-ray detection capabilities of vertical β-Ga2O3 Schottky photodiodes on a bulk (100) β-Ga2O3 substrate that was grown by an edge-defined film-fed growth (EFG) method. Both the static and transient responses of the fabricated detectors to X-ray illumination were characterized, and a strong trap-related photoconductive effect was observed in addition to the photovoltaic mechanism. The responsivity of the detectors was calculated to be 1.8 μC/Gy at a reverse bias of −25.8 V. The response time was studied though fitting the transient photocurrent using the exponential decay functions. Associated with material characterizations, it was revealed that the existence of oxygen vacancies within the β-Ga2O3 substrate weakened the performances of the X-ray detectors, mainly their sensitivity and response speed.