Realization of High-Performance Solar-Blind Ultraviolet Detection through Substrate and Bandgap Engineering: Construction and Mechanism of the STO/Ga ₂ O ₃ Heterojunction

Solar-blind ultraviolet (SBUV) photodetectors are in high demand for applications such as missile warning, flame sensing, and non-line-of-sight communication. However, the development of detectors that simultaneously possess high sensitivity, low power consumption, and a fast response speed remains a challenge. This work demonstrates the epitaxial growth of high-quality, 1 μm-thick gallium oxide (Ga 2 O 3 ) films on strontium titanate (SrTiO 3 or STO) (001) single-crystal substrates via magnetron sputtering for constructing metal–semiconductor–metal (MSM) SBUV photodetectors. The device exhibits outstanding comprehensive performance at a low operating voltage of 5 V: a responsivity of 0.22 A/W and a corresponding detectivity of 1.91 × 10 13 Jones, indicating an excellent capability for weak light signal detection. Simultaneously, under a 1 V bias, it demonstrates an extremely low dark current of 2.1 × 10 –12 A and a high photo-to-dark current ratio (PDCR) of ∼10 5, which significantly improves the signal-to-noise ratio and anti-interference capability. Furthermore, the device exhibits clear fast switching characteristics with rise and fall times of 48.06 and 9.12 ms, respectively. These results indicate that Ga 2 O 3 films epitaxially grown on STO substrates constitute an ideal material system for constructing high-performance, low-power-consumption SBUV photodetectors, showing great application potential in next-generation optoelectronic devices.