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 Hz1/2 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.