A van der Waals stacked CdS /WSe2 heterostructure for high-performance photodetection

Abstract

Transition metal dichalcogenides have garnered growing attention in optoelectronic applications owing to their unique physicochemical properties and efficient carrier transport capabilities. However, their atomic-scale thickness severely limits their light absorption efficiency. Herein, we fabricated a van der Waals stacked heterostructure conveniently and efficiently via transferring a CdS nanobelt onto a bilayer WSe₂ nanosheet. Benefiting from the formation of a type-II band alignment between WSe₂ and CdS, the CdS/WSe₂ photodetector achieves a high responsivity of 643.9/1315.5 A/W and an outstanding specific detectivity of 2.89 × 10¹³/5.91 × 10¹³ Jones under weak 450/520 nm light irradiation. Moreover, the p–n junction formed between p-type WSe₂ and n-type CdS effectively suppresses the dark current, leading to a 1591.5× (194.5×) enhancement in the on/off ratio compared to the pure CdS (pure WSe₂) control devices. This work demonstrates the great potential of vdW stacked heterostructures for high-performance photodetection and provides new insights into the development of advanced optoelectronic devices.