Performance enhancement of α-Ga2O3-based deep-ultraviolet photodetectors through back-side illumination

Deep-ultraviolet (DUV) photodetectors (PDs) require wide-bandgap semiconductors to achieve excellent solar-blind performance, and gallium oxide (Ga 2 O 3 ) has emerged as a promising material for next-generation DUV PDs. α-Ga 2 O 3 -based DUV PDs have been studied, but their slow photoresponse speed still remains a challenge. In this study, α-Ga 2 O 3 thin films were grown by hydride vapor phase epitaxy (HVPE), followed by rapid thermal annealing (RTA), and fabricated into DUV PDs with a metal–semiconductor–metal (MSM) configuration. The RTA process reduced oxygen-vacancy-related defects, thereby improving overall device performance, including photoresponse speed. Moreover, it was noted that back-side illumination, in which light enters the active layer through the substrate, enhanced carrier generation and collection compared to front-side illumination, thereby accelerating the photoresponse. Measurement results showed that the device annealed by RTA for 5 min exhibited, under back-side illumination at 230 nm, a responsivity of 2.95 A W −1 , a detectivity ( 𝐷 * ) of 9.74 × 10 13 Jones, and an external quantum efficiency (EQE) of 1590%. The turn-on response time was 0.886 s, representing a 62% reduction compared to front-side illumination (2.352 s). These findings emphasize the complementary contributions of RTA process and back-side illumination, offering a practical strategy for developing high-performance α-Ga 2 O 3 -based DUV PDs for advanced optoelectronic applications.