Layered metal monochalcogenides have attracted significant interest in the 2D family since they show different unique properties from their bulk counterparts. The comprehensive synthesis, characterization, and optoelectrical applications of 2D‐layered tin monosulfide (SnS) grown by pulsed laser deposition are reported. Few‐layer SnS‐based field‐effect transistors (FETs) and photodetectors are fabricated on Si/SiO2 substrates. The premium 2D SnS FETs yield an on/off ratio of 3.41 × 106, a subthreshold swing of 180 mV dec−1, and a field effect mobility (µFE) of 1.48 cm2 V−1 s−1 in a 14‐monolayer SnS device. The layered SnS photodetectors show a broad photoresponse from ultraviolet to near‐infrared (365–820 nm). In addition, the SnS phototransistors present an improved detectivity of 9.78 × 1010 cm2 Hz1/2 W−1 and rapid response constants of 60 ms for grow‐time constant τg and 10 ms for decay‐time constant τd under extremely weak 365 nm illumination. This study sheds light on layer‐dependent optoelectronic properties of 2D SnS that promise to be important in next‐generation 2D optoelectronic devices.
In article number 1901020, Xinhua Pan, Yu‐Jia Zeng, Chris Van Haesendonck, and co‐workers successfully grow 2D layered tin monosulfide (SnS) by pulsed laser deposition. They demonstrate how the properties of SnS depend on the number of monolayers. This study sheds light on the layerdependent properties of 2D SnS, a material that promises to be important in 2D optoelectronic devices.
Experimental evidence of topological Dirac fermion charge carriers in pure and robust α‐Sn thin films grown on InSb substrates is reported. This evidence is acquired using standard macroscopic four‐point contact resistance measurements, conducted on uncapped films with a significantly reduced bulk mobility. The electrical characteristics of the constituting components of the α‐Sn/InSb sample are analyzed and compared and a three‐band drift velocity model is proposed accordingly. A surface band, with low carrier density and high mobility, is identified as the origin of the observed Shubnikov – de Haas (SdH) oscillations. The analysis of these quantum oscillations results in a nontrivial value of the phase shift γ0, characteristic of topologically protected Dirac fermions. The momentum relaxation time τ ≈ 300 fs in pure, undoped α‐Sn thin films is estimated.
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