Layer‐Dependent Optoelectronic Properties of 2D van der Waals SnS Grown by Pulsed Laser Deposition

Abstract

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.

Novel Self-Powered Photodetector with Binary Photoswitching Based on SnSx/TiO2 Heterojunctions

“…The additional peak at 160 cm −1 in SnS x nanoflakes grown for 60 min is the B 3g mode of the SnS phase structure induced by the improved orientation. Among the Raman-active modes, the Raman peaks at 92.5 and 229.3 cm −1 are attributed to the A g mode corresponding to "waving" and the Sn atoms vibrate against the S atoms in SnS, 34 whereas there is a peak at 314.5 cm −1 assigned to the A 1g mode of SnS 2 phases in SnS x nanoflakes. 35,36 The coexistence of 92.5 and 314.5 cm −1 peaks confirms the mixed phases of SnS x by SnS and SnS 2 .…”

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“…68 A higher D* value of any photodetector signifies its suitability in weak signal detection. 69 Some photosensing parameters (J d , J ph , R λ , D*, and τ) are shown in Table 1.…”

“…Next, the detectivity ( D *) is a figure of merit of a photodetector, which is evaluated using equation , where q is the charge of an electron . A higher D * value of any photodetector signifies its suitability in weak signal detection . Some photosensing parameters ( J d , J ph , R λ , D *, and τ) are shown in Table .…”

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“…The photocurrent ( I light ) of S1, S2, and S3 are 6.46 × 10 −6 , 1.75 × 10 −5 , and 4.15 × 10 −5 A, and the dark current ( I dark ) of S1, S2, and S3 are 3.5 × 10 −10 A, 4 × 10 −9 A, and 2.36 × 10 −8 A, respectively. The responsivity ( R ), an important parameter to evaluate the sensitivity of the PDs, can be calculated by the following Equation () [ 6 ] where I light is the photocurrent, I dark is the dark current, P is the intensity of the incident lights (1074 mW cm −2 ), and S is the effective area of the PD ( S = 0.005 cm 2 ). The R λ values are calculated to be 1.22, 3.24, and 7.67 mA W −1 for S1, S2, and S3, respectively.…”

“…[ 1–4 ] More attentions have recently been focused on broadband PDs that can sense light from the ultraviolet–visible (UV–Vis) to the infrared (IR) region. [ 5,6 ] In addition, self‐powered PDs, which can work independently, wirelessly, and sustainably, have attract intensive attentions to meet the demands of weightless, small size, and low power consumption for the next‐generation optoelectronic devices. Typically, self‐powered PDs can be divided into two categories: [ 7 ] One is designed by utilizing the photovoltaic effect.…”