Bandgap-Tuned Yttrium-Doped Indium Oxide Alloy Thin Films for High-Performance Solar-Blind Ultraviolet Photodetectors

Yttrium oxide (Y2O3) has emerged as a key material for advanced solar-blind ultraviolet (SBUV) photodetectors, attributable to its large bandgap energy (~5.5 eV), high dielectric constant, excellent silicon compatibility, and robust thermal stability. To precisely tune its optical bandgap for optimal alignment with the intrinsic solar-blind region, this study prepared Y1.5In0.5O3 ternary alloy films via co-sputtering, achieving an optimized bandgap of 4.70 eV. After optimizing the photosensitive layer, we fabricated a self-powered Pt/Y1.5In0.5O3/p-GaN back-to-back heterojunction SBUV photodetector was fabricated based on the optimized photosensitive layer. Under photovoltaic operation (0 V), the resulting device exhibited impressive performance metrics: a narrow spectral response (FWHM ~50 nm), quick rise/decay times of 30 and 75 ms, respectively, and high operational durability (less than 0.8% photocurrent degradation over 100 cycles). The detector also maintained a low noise current level (2.95 × 10−12 A/Hz1/2 at 1 Hz) and a low noise-equivalent power (NEP) of 4.42 × 10−9 W/Hz1/2, indicating high sensitivity to weak optical signals. These results establish YxIn2−xO3 ternary alloy as a viable material platform for SBUV detection and provide a new design strategy for developing highly sensitive, low-noise and spectrally selective ultraviolet photodetectors.