Ultrahigh-efficiency solar-blind ultraviolet detection with a <b> <i>β</i> </b> -Ga2O3/Si heterojunction

To overcome the limitations of low responsivity (R) and suboptimal spectral selectivity inherent in silicon (Si)-based solar-blind ultraviolet (SBUV) photodetectors (PDs), as well as the challenges posed by the low electron mobility and polycrystalline structure of heteroepitaxial β gallium oxide (β-Ga2O3), a high-electron-mobility PD utilizing a β-Ga2O3/Si heterojunction is developed. In this PD, β-Ga2O3 serves as the SBUV absorption layer, capitalizing on its high responsivity and spectral selectivity, while Si acts as the photogenerated electron transport layer, leveraging its superior crystalline quality and electron mobility to form a complementary system. The resulting PD achieves a remarkable R of 6.67 × 105 A/W and an external quantum efficiency of 3.25 × 108%, coupled with exceptional spectral selectivity. This study provides valuable guidance for SBUV applications of both Si and β-Ga2O3.