A high-performance self-powered solar-blind UV photodetector based on an annealed Sc0.74In1.26O3 ternary alloy film

Abstract

Scandium oxide (Sc₂O₃) exhibits significant potential in the field of high-performance solar-blind ultraviolet (SBUV) photodetectors due to its ultra-wide bandgap (5.2–6.3 eV) and excellent thermal and chemical stabilities. To precisely tune the bandgap of Sc₂O₃ to match the intrinsic SBUV region (4.4–6.2 eV), this study successfully prepared Sc_0.74In_1.26O₃ ternary alloy films using a co-sputtering method, modulating the bandgap to 4.65 eV. Subsequently, a high-performance self-powered Pt/Sc_0.74In_1.26O₃/p-GaN back-to-back heterojunction SBUV photodetector was fabricated based on the prepared Sc_0.74In_1.26O₃ photosensitive layer. The study reveals that the photodetector performance is significantly enhanced after annealing the Sc_0.74In_1.26O₃ film. At a bias of 0 V, the photodetector demonstrates outstanding comprehensive performance, including an extremely low dark current (∼2 pA), a high photo-to-dark current ratio (PDCR, > 10³), a narrow spectral response full width at half maximum (FWHM, ∼45 nm), a high UV-to-visible rejection ratio (>10³), fast response speeds (a rise time of 168 ms and a decay time of 261 ms), and excellent stability and repeatability (only a 0.5% variation in photocurrent after 50 cycles). Mechanistic investigations indicate that the significant improvement in device performance after annealing is primarily attributed to enhanced crystallinity and reduced oxygen vacancies in the Sc_0.74In_1.26O₃ film. The Sc_0.74In_1.26O₃ ternary alloy film photosensitive layer proposed in this study provides a new material choice and design strategy for developing SBUV photodetectors with high signal-to-noise ratios and spectral selectivity.