Tin Disulfide—An Emerging Layered Metal Dichalcogenide Semiconductor: Materials Properties and Device Characteristics

Abstract

Layered metal dichalcogenides have attracted significant interest as a family of single- and few-layer materials that show new physics and are of interest for device applications. Here, we report a comprehensive characterization of the properties of tin disulfide (SnS2), an emerging semiconducting metal dichalcogenide, down to the monolayer limit. Using flakes exfoliated from layered bulk crystals, we establish the characteristics of single- and few-layer SnS2 in optical and atomic force microscopy, Raman spectroscopy and transmission electron microscopy. Band structure measurements in conjunction with ab initio calculations and photoluminescence spectroscopy show that SnS2 is an indirect bandgap semiconductor over the entire thickness range from bulk to single-layer. Field effect transport in SnS2 supported by SiO2/Si suggests predominant scattering by centers at the support interface. Ultrathin transistors show on-off current ratios >10(6), as well as carrier mobilities up to 230 cm(2)/(V s), minimal hysteresis, and near-ideal subthreshold swing for devices screened by a high-k (deionized water) top gate. SnS2 transistors are efficient photodetectors but, similar to other metal dichalcogenides, show a relatively slow response to pulsed irradiation, likely due to adsorbate-induced long-lived extrinsic trap states.

Booming Development of Group IV–VI Semiconductors: Fresh Blood of 2D Family

“…In general, GIVMCs have been classified into two groups according to their chemical compositions: MX (SiC,89 SiS,90 GeS,91, 92 GeSe,93, 94, 95, 96 SnS,97, 98, 99 SnSe,100, 101, 102, 103, 104, 105, 106, 107, 108 SnTe,109, 110) and MX 2 (GeS 2 ,111 GeSe 2 ,112, 113, 114, 115 SnS 2 ,72, 116, 117, 118 SnSe 2 73, 119, 120, 121, 122, 123, 124, 125). In this part, some typical GIVMCs are presented in Table 1 .…”

“…g) Comparison of the calculated band structure of bulk (4H) and monolayer SnS 2 . (d–g) Reproduced with permission 72. 2014, American Chemical Society.…”

“…Raman spectroscopy is a useful instrument to verify the crystal phase and make a distinction between bulk and few or mono layered counterparts of 2DLMs 71, 72, 131. Generally, metal chalcogenides could crystallize to the following phases such as 2H, 4H, and 1T structures.…”

“…In addition, GIVMCs have demonstrated excellent performance in FETs and photodetectors. For example, SnS 2 has illustrated a relatively high carrier mobility up to 230 cm 2 (V −1 s −1 ) and on–off current ratios over 10 6 ,72 comparable or even surpassing many other 2DLMs 84, 85, 86, 87, 88. Ultrathin SnSe 2 nanosheets have shown high responsivity of above 10 3 A W −1 with a fast response time of ≈8 ms 76…”

“…Among the 2DLMCs, group IV metal chalcogenides (GIVMCs, metal = Ge, Sn; chalcogen = S, Se, Te) provide an opportunity for sustainable electronic and photonic systems recently due to the low‐cost, earth‐abundant, and environmentally friendly features69 In 2013, ultrathin GIVMCs have been mechanically exfoliated for high performance FETs such as SnS 2 ,70, 71, 72 SnSe 2 ,73 SnS 2–x Se x 74. In view of the difficulty in large‐scale synthesis via mechanical exfoliation, Peng and co‐workers75 in 2015 demonstrated for the first time the controlled synthesis of thin SnS 2 nanosheets arrays by predefined metal seeds with the average thickness of 20 nm, thereby providing a new approach to the large‐scale production.…”