Nano-Interface ChargeTransfer in Ga₂O₃@(Co, Ni)S₂ HeterojunctionUltraviolet Photodetectors

Constructing nanoheterojunction is a crucial approach to achieving self-powered ultraviolet photodetectors based on Ga₂O₃. Two-dimensional modified NiS₂ nanosheets are excellent candidates for fabricating nanoheterojunctions due to their high electrical conductivity for efficient charge transport, large surface area for enhanced light absorption, and exceptional chemical and thermal stability for reliable long-term UV detection. Herein, two-dimensional bimetallic (Co, Ni)S₂ nanosheets are proposed using a two-step hydrothermal synthesis method. Subsequently, a 3<i>D</i>/2D Ga₂O₃@(Co, Ni)S₂ heterojunction is constructed by depositing (Co, Ni)S₂ nanosheets onto the Ga₂O₃ nanowire network. Ga₂O₃@(Co, Ni)S₂ heterojunction photodetector achieves a self-driven responsivity of 36.56 mA W^1– under 254 nm illumination, which is higher than the heterojunction photodetector based on Ga₂O₃ and monometallic NiS₂ photodetector. Under 10 V bias, Ga₂O₃@(Co, Ni)S₂ heterojunction photodetector exhibits a high responsivity, detectivity, and external quantum efficiency of 1.51 A W^1–, 7.68 × 10¹² Jones, and 738.27%, which are 174.11, 8.95, and 174.11 times greater than those of pure Ga₂O₃ photodetector. The Ga₂O₃@(Co, Ni)S₂ photodetector also displays a faster response speed than that of the pure Ga₂O₃ photodetector. Calculated charge density differences show that improved performances are attributed to the advanced band alignment and interface charge transfer by forming the type I heterostructure between Ga₂O₃ and (Co, Ni)S₂. The established built-in electric field and lower Schottky barrier facilitate the effective transfer of photoelectrons at the nanointerface. Furthermore, the enhanced light absorption capacity and elevated conductivity of (Co, Ni)S₂ contribute to the improved photoelectric conversion capability. This research highlights that 2D bimetallic sulfide nanomaterials play a significant role in developing Ga₂O₃-based self-driven photodetectors.