SnS$_{2}$: An Emerging Layered Metal Dichalcogenide Semiconductor

Layered materials are of interest for new physics and due to their promise for device applications. Recent research has extended from graphene to transition metal metal dichalcogenides, with a strong focus on MoS$_{2}$. Here, we report a comprehensive study of a new group IV metal dichalcogenide, tin disulfide (SnS$_{2})$ [1]. Using flakes exfoliated from bulk crystals, we establish the characteristics of single- and few-layer SnS$_{2}$ in optical and atomic force microscopy, Raman spectroscopy and transmission electron microscopy. Band structure study show that SnS$_{2}$ is an indirect gap semiconductor over the entire thickness range from bulk to a single layer. Ultrathin transistors screened by a liquid gate show promising characteristics, such as on-off current ratios \textgreater 10$^{6}$, high carrier mobilities (up to 230 cm$^{2}$ V$^{-1}$s$^{-1})$, minimal hysteresis and near-ideal subthreshold swing. SnS$_{2}$ transistors are efficient photodetectors, but similar to other dichalcogenides show a relatively slow response to pulsed irradiation, likely due to adsorbate-induced long-lived extrinsic trap states. \\[4pt] [1] Y. Huang et al., ACS Nano 8, 10343 (2014).