Localized electric-field-enhanced low-light detection by a 2D SnS visible-light photodetector

• Published in: Chinese physics B Vol. 30; no. 5; pp. 57803 - 745
• Main Authors: Wen, Hao, Xiong, Li, Tan, Congbing, Zhu, Kaimin, Tang, Yong, Wang, Jinbin, Zhong, Xiangli
• Format: Journal Article
• Language: English
• Published: School of Materials Science and Engineering,Xiangtan University,Xiangtan 411105,Hunan,China 01.05.2021
• Subjects: two-dimensional SnS; low-light detection; photogating effect
• ISSN: 1674-1056
• DOI: 10.1088/1674-1056/abd7db

Due to their excellent carrier mobility, high absorption coefficient and narrow bandgap, most 2D IVA metal chalcogenide semiconductors (GIVMCs, metal = Ge, Sn, Pb; chalcogen = S, Se) are regarded as promising candidates for realizing high-performance photodetectors. We synthesized high-quality two-dimensional (2D) tin sulfide (SnS) nanosheets using the physical vapor deposition (PVD) method and fabricated a 2D SnS visible-light photodetector. The photodetector exhibits a high photoresponsivity of 161 A⋅W −1 and possesses an external quantum efficiency of 4.45 × 10 4 %, as well as a detectivity of 1.15 × 10 9 Jones under 450 nm blue light illumination. Moreover, under poor illumination at optical densities down to 2 mW⋅cm −2 , the responsivity of the device is higher than that at stronger optical densities. We suggest that a photogating effect in the 2D SnS photodetector is mainly responsible for its low-light responsivity. Defects and impurities in 2D SnS can trap carriers and form localized electric fields, which can delay the recombination process of electron-hole pairs, prolong carrier lifetimes, and thus improve the low-light responsivity. This work provides design strategies for detecting low levels of light using photodetectors made of 2D materials.