High-Sensitivity UV–visible Photodetectors Based on SnS 2 Nanosheet/CdS Nanobelt Composites

Tin disulfide (SnS 2 ) stands out for its high absorption coefficient and efficient light absorption in the ultraviolet (UV) spectrum. However, the intrinsic defect-induced Fermi energy level pinning in tin disulfide limits its further utilization in optoelectronic detection. To overcome these shortcomings, high-quality, large-size SnS 2 nanosheets and cadmium sulfide (CdS) nanobelts were prepared by chemical vapor deposition (CVD) and physical vapor deposition (PVD), respectively. A SnS 2 Nanosheet/CdS nanobelt composite photodetector was fabricated and investigated. It is found that the composite photodetector exhibits superior performance in detecting UV–visible wavelengths. Compared to the SnS 2 -based photodetector, the composite device demonstrates a higher responsivity (9760.4 A/W), a remarkable on/off current ratio ( I on / I off ) of 1.36 × 10 6, rapid rise/decay time of 115/454 μs, a large external quantum efficiency of 3.46 × 10 6 % and a specific detectivity of 4.36 × 10 13 Jones. These outstanding properties are attributed to the high-quality crystal structure of the SnS 2 nanosheets and CdS nanobelts, as well as the formation of a type II energy band structure, which effectively separates charge carriers. A reliable imaging capability is exhibited by the SnS 2 /CdS composite photodetector under ultraviolet illumination. The SnS 2 -based photodetector shows great potential for the development of future optoelectronic devices.