Enhancing Ga₂O₃ Solar-Blind Photodetectors via Metal Nanogratings

Solar-blind ultraviolet photodetectors (SBUV-PDs) are utilized in various military and civilian fields, encompassing missile tracking, high-voltage detection, and fire warning systems. Ga2O3 emerges as the prime candidate for such PDs owing to its elevated bandgap, remarkable thermal stability, and facile fabrication process. The metal-semiconductor–metal (MSM) structure garners attention for its swift response time and straightforward preparation, thus becoming a focal point among diverse PD architectures. Nevertheless, the metal surface impedes optical absorption, thereby diminishing the quantum efficiency of the PD. In this work, we introduce a nanograting onto the Ga2O3 surface, which results in a 747-fold increase in responsivity in the SBUV region compared to a normal MSM grating-free structure. Metal gratings can induce surface plasmon polaritons (SPP), thereby augmenting the optical absorption of the PD and stimulating hot electrons to increase photocurrent. However, the broadband response caused by the introduction of metal gratings is a common problem. By optimizing the doping concentration of the Ga2O3 absorption layer, adjusting the incident light intensity, and reverse voltage, the problem of broadband response has been solved. The responsivity of the device in the non-SBUV region is suppressed 24-fold. This methodology holds promise as a reliable approach for fabricating high-performance SBUV-PDs.