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 (Ga2O3) films on strontium titanate (SrTiO3 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 × 1013 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 ∼105, 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 Ga2O3 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.