High-performance photodetectors based on two-dimensional tin(ii) sulfide (SnS) nanoflakes

Abstract

As a kind of two-dimensional (2D) materials, tin sulfides including tin(IV) sulfide (SnS₂) and tin(II) sulfide (SnS) have been attracting wide attention because of its earth abundance, low cost, and environment-friendly characteristics as promising photovoltaic and photocatalytic materials. Among them, only SnS is a p-type semiconductor with appealing physical properties. However, its further investigation and functionalization have been hampered by the absence of highly crystallized nanostructures relative to other intensively studied tin sulfides, such as tin(IV) sulfide (SnS₂). Herein, high quality 2D SnS is synthesized via the chemical vapor deposition (CVD) method, with a new precursor of stannous oxide (SnO). Its morphology and properties are characterized by optical microscopy (OM), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive spectrometry (EDS), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Furthermore, field-effect transistors (FETs) and photodetectors based on such SnS are fabricated using Photolithographic-Pattern-Transfer (PPT) technology. The results show that the as-grown SnS is indeed a p-type semiconductor and exhibits high responsivity (156.0 A W⁻¹), normalized detectivity (2.94 × 10¹⁰ jones) and external quantum efficiency (4.77 × 10⁴%) with fast response time (5.1 ms) under illumination of a 405 nm laser. This work demonstrates that 2D SnS holds great promise for next-generation optoelectronic applications.