A synergistic heterojunction of SnS2/SnSSe nanosheets on GaN for advanced self-powered photodetectors†

Tin-based TMDCs are gaining traction in optoelectronics due to their eco-friendliness and easy synthesis, contrasting Mo/W-based counterparts. This study pioneers the solvothermal synthesis of highly crystalline SnSSe alloy, akin to Janus structures, bridging a notable research gap. By integrating SnS₂/SnSSe materials onto a GaN platform, a synergistic heterojunction is created, enhancing light absorption and the electron–hole pair separation efficiency, demonstrating a self-powered photodetection. The GaN/SnS₂/SnSSe heterojunction showcases a staircase-like (type-II) band alignment and exceptional performance metrics: high photoresponsivity of 314.96 A W⁻¹, specific detectivity of 2.0 × 10¹⁴ jones, and external quantum efficiency of 10.7 × 10⁴% under 365 nm illumination at 150 nW cm⁻² intensity and 3 V bias. Notably, the device displays intensity-dependent photocurrent and photoswitching behaviors without external bias, highlighting its unique self-powered attributes. This study underscores SnS₂'s significance in optoelectronics and explores SnSSe integration into van der Waals heterostructures, promising advanced photodetection devices and bias-free optoelectronics.