MBE-Grown MgO Thin Film Vacuum Ultraviolet Photodetector with Record High Responsivity of 3.2 A/W Operating at 400 °C

In this work, a high performance vacuum ultraviolet (VUV) photodetector (PD) based on MgO thin film has been fabricated and characterized from room temperature to 400 °C for the first time. At 25 °C, the device exhibits a low dark current of 100 fA, a large VUV/UVC rejection ratio of over 10 ⁴ , a high responsivity of 0.865 A/W under 185 nm illumination, and a short response time of 1.25 μs at the bias of 20 V. The excellent thermal stability has also been demonstrated even at high temperature up to 400 °C, exhibiting a record-high responsivity (3.2 A/W), a maintained quick response speed (1.25 μs) and a large VUV/UVC rejection ratio (>10 ³ ), which is obviously better than any other reported VUV detectors based on ultra-wide bandgap semiconductors. Additionally, this MgO PD demonstrates exceptional repeatability and long-term operating stability at both room temperature and elevated temperature. These findings underscore the outstanding performance of the MgO VUV PD, rendering it highly suitable for demanding operational conditions.