Enhancing Performance of GaN/GaO P-N Junction Uvc Photodetectors via Interdigitated Structure.

GaO-based Ultraviolet-C photodetector (UVCPD) is considered the most promising UVCPD at present and is divided into Metal-Semiconductor-Metal (MSM) and PN junction types. Compared with MSM-PDs, PN-PDs exhibit superior transient performance due to the built-in electric field. However, current GaO-based PN-PDs lack consideration for carrier collection and electric field distribution. In this study, PN-PDs with an interdigital n-GaO layer and finger electrodes are fabricated on p-GaN/n-GaO epilayers. Ultrafast response times of 31 µs (1/e decay) and 2.76 µs (fast component) are realized, which outperforms all GaO UVC-PDs up to now. Under 0 V self-powered, the responsivity (0.25 A W) of interdigital PD is enhanced by the interdigital electrode structure due to increasing carriers' collection length. Under bias, the performances of interdigital PD with 41.7 A W responsivity and 8243 selection ratios are significantly elevated by enhancing the built-in electric field in the GaO region, which is 34.76 and 39.4 times those of traditional PDs, respectively. The intrinsic enhancing mechanism of interdigital structure is also investigated by interdigital PDs with various electrode spacings and perimeters. In summary, this paper not only reports a highly performed interdigitated structure p-GaN/n-GaO UVCPDs, but also provides guidelines for structure design in GaO-based PN-PDs.