Enhanced performance of Ga₂O₃-based MSM-PD by Fabry–Pérot microcavity

Ga₂O₃-based metal-semiconductor-metal (MSM) solar-blind photodetectors, valued for their wide bandgap and stability, are among the most promising options. However, key metrics such as detectivity, wavelength selectivity, and response time were largely constrained by the intrinsic properties of Ga₂O₃ and were difficult to enhance through optical design due to the fixed device structure. To address this, this study introduced a distributed Bragg reflector (DBR) structure in the UVC band between the sapphire substrate and Ga₂O₃ epilayer, forming a Fabry-Pérot (FP) resonant cavity with the Ga₂O₃/air interface. The incorporation of the FP microcavity significantly enhanced the UVC photon density of states (<i>DOS</i>) within the Ga₂O₃ thin film while suppressing that of other wavelength bands. As a result, the selectivity ratio was improved by 29.4 times (<i>R</i>_251<i>nm</i>/<i>R</i>_360<i>nm</i>=1.6×10⁴), and the device's detectivity as well as rise/fall times were also optimized. This work provided a novel, to the best of our knowledge, design strategy for high-performing solar-blind PDs.