Robust Self-Powered UV Detector Based on a h-ZnTiO3:Ta/p-GaN Epitaxial Heterojunction for High-Temperature Application

A self-powered photodetector based on a Ta-doped ZnTiO₃/p-GaN single-crystal p–n heterojunction with a cross-finger (CF) structure is fabricated. Compared with the flat-plate structure, the CF-type photodetector presented higher photoresponsivity in a wavelength range of 250–350 nm. At zero bias, the UV photodetector with a CF structure exhibits excellent detection performance, including a high responsivity of 0.73 A/W, a good detectivity of 3.98 × 10¹² Jones, and a fast response time of 42.2/10.2 ms. The band composition and working mechanism of the heterojunction detector are elucidated accordingly. Besides, benefiting from the single-crystal structure, the h-ZnTiO₃:Ta/p-GaN heterojunction self-powered detector maintains robust detection for UV signals at high temperatures. Compared to room temperature, even at 200 °C, the performance of the device only slightly deteriorates, with a responsivity of 0.66 A/W, a detectivity of 2.19 × 10¹² Jones, and a response time of 46.2/11.9 ms. This work provides a good candidate for a stabilized self-powered UV detector applied in high-temperature environments.