Visible-to-near-infrared photodetectors based on SnS/SnSe₂ and SnSe/SnSe₂ p−n heterostructures with a fast response speed and high normalized detectivity

Abstract The emergent two-dimensional (2D) material, tin diselenide (SnSe2), has garnered significant consideration for its potential in image capturing systems, optical communication, and optoelectronic memory. Nevertheless, SnSe2-based photodetection faces obstacles, including slow response speed and low normalized detectivity. In this work, photodetectors based on SnS/SnSe2 and SnSe/SnSe2 p−n heterostructures have been implemented through a polydimethylsiloxane (PDMS)−assisted transfer method. These photodetectors demonstrate broad-spectrum photoresponse within the 405 to 850 nm wavelength range. The photodetector based on the SnS/SnSe2 heterostructure exhibits a significant responsivity of 4.99 × 103 A∙W−1, normalized detectivity of 5.80 × 1012 cm∙Hz1/2∙W−1, and fast response time of 3.13 ms, respectively, owing to the built-in electric field. Meanwhile, the highest values of responsivity, normalized detectivity, and response time for the photodetector based on the SnSe/SnSe2 heterostructure are 5.91 × 103 A∙W−1, 7.03 × 1012 cm∙Hz1/2∙W−1, and 4.74 ms, respectively. And their photodetection performances transcend those of photodetectors based on individual SnSe2, SnS, SnSe, and other commonly used 2D materials. Our work has demonstrated an effective strategy to improve the performance of SnSe2-based photodetectors and paves the way for their future commercialization.