High-performance visible-to-near infrared phototransistor based on SnSe/SnS2 van der Waals heterostructure†

As a member of two-dimensional materials, tin disulfide (SnS₂) holds great potential for highly sensitive detectors used in high-resolution, low-power imaging. Nevertheless, SnS₂-based detectors face challenges, such as a narrow detection range, low responsivity, and slow response speed. In this work, gate-modulated phototransistors based on a tin monoselenide/tin disulfide (SnSe/SnS₂) heterostructure were fabricated, demonstrating a spectral response from visible to near-infrared. The phototransistors exhibited a maximum responsivity of 2667.1 A W⁻¹ and an extremely high detectivity of 1.02 × 10¹³ cm Hz^1/2 W⁻¹ under 405 nm illumination. Additionally, they exhibited an extremely high responsivity of 537.6 A W⁻¹ and a high external quantum efficiency of 78.3 × 10⁴% under 850 nm illumination. The photodetection performance could be modulated by the back-gate voltage. At a back-gate voltage of 50 V, the phototransistor achieved an enhanced responsivity of 4002.9 A W⁻¹, surpassing detectors based on individual components and most other two-dimensional materials. This work provides an effective strategy for achieving gate-modulated photodetection performance and broadens the scope of applications for SnS₂-based detectors.