Enhanced Optoelectronic Performance of Silicon Nanowire/SnS2 Core-Shell Heterostructure With Defect Passivation in SnS2 by UV Treatment

Recently, metal-dichalcogenides (MDs) have much attention for future optoelectronic device due to their unique electronic and optical properties. However, structural defect incorporated during synthesis process traps free charge carriers and limits its application to device integration. Therefore, defect passivation in MDs is an important aspect to investigate for future application. Here, we have reported ultraviolet (UV) treatment as a successive defect passivation technique on SnS ₂ , one of the MD materials. In this study, we measured the photodetector characteristics of SiNWs/SnS ₂ core-shell heterostructure before and after UV treatment and found extensive improvement in photodetector’s figure-of-merit parameters. The UV-treated heterostructure exhibits high responsivity ( $\boldsymbol \Re {)}$ and excellent external quantum efficiency (EQE) and fast response speed with a maximum value of $\sim $ 990 A/W and $\sim 10^{{6}}$ %, 10 ms (rise time, $\boldsymbol \tau _{r}{)}$ , and 70 ms (decay time, $\boldsymbol \tau _{d}{)}$ , respectively, at 340-nm wavelength and is much better compared to normal device ( $\boldsymbol \Re \sim $ 145 A/W, EQE $\sim 10^{{4}}$ , $\boldsymbol \tau _{r}\sim 260$ ms, and $\boldsymbol \tau _{d}\sim 75$ ms). This improvement is due to the reduction of deep-level defect states in SnS ₂ , which is confirmed by the photoluminescence (PL) and Raman analysis. This study will help us better understand the electronic and optical properties of SnS ₂ by passivating the defect state with UV treatment.