Electronic and optical properties of single crystal SnS2: an earth-abundant disulfide photocatalyst (original) (raw)
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ptical properties of single crystal SnS 2 : an earth-abundant disul fi de photocatalyst †
2015
Materials and Structures Laboratory, To Nagatsuta, Midori-ku, Yokohama 226-8503 jp; Tel: +81-45-924-5345 Stephenson Institute for Renewable Energ Liverpool, Liverpool, L69 7ZF, UK Centre for Sustainable Chemical Technologi Bath, Bath, BA2 7AY UK Department of Engineering Science, Univer 3PJ, UK School of Physics, HH Wills Physics Laborat Bristol, BS8 1TL, UK School of Chemistry, Cardiff University, Par School of Chemistry, University of Bristol, C Global E Institute and Department of M University, Seoul 120-749, Korea † Electronic supplementary informa 10.1039/c5ta08214e Cite this: J. Mater. Chem. A, 2016, 4, 1312
Optical spectroscopy of 1T-tin disulfide single crystal
The Journal of Physical Chemistry, 1993
The present paper discuss the characterization of the bandgap and midbandgap optical properties of a high quality 1 T-SnS2 single crystals. These crystals were grown by chemical vapor transport method with predominantly low concentration of iodine. The optical properties were characterized by the following complementary measurements: transmission, photoluminescence (PL) (at various temperatures and excitation power), time resolved PL and PL decay processes. The results indicate that the luminescence events are associated with donor-acceptor recombination process of pairs with ensemble average of distances. Theoretical simulation of the luminescence decay process included comparison of a two-and three-dimensional recombination mechanisms. Chemical characterization in combination with the theoretical results support the possibility of a n interaction among intralayer acceptors (metal vacancies) with van der Waals donors (intrinsic or extrinsic impurities).
Solid state synthesis and spectral investigations of nanostructure SnS2
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014
Nanometer sized SnS 2 particles were synthesised by solid state reaction between tin chloride and thiourea in air at 150-350°C. The structural, morphological and optical properties were characterized by using X-ray diffraction (XRD), FT-IR, FT-Raman, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL) and UV-Vis spectra. The X-ray diffraction (XRD) pattern of the product was indexed to the hexagonal phase of SnS 2. Crystallite size, microstrain and dislocation density were evaluated from the XRD data. EDS analysis indicated that the elemental ratio was similar to tin disulphide (SnS 2). The blue shift in the absorption edge was observed from the UV-Vis spectrum. The Photoluminescence spectra showed two emission peaks corresponding to blue and red emission.
ACS Nano, 2014
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 (SnS 2 ), an emerging semiconducting metal dichalcogenide, down to the monolayer limit. Using flakes exfoliated from layered bulk crystals, we establish the characteristics of single-and fewlayer SnS 2 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 SnS 2 is an indirect bandgap semiconductor over the entire thickness range from bulk to single-layer. Field effect transport in SnS 2 supported by SiO 2 /Si suggests predominant scattering by centers at the support interface. Ultrathin transistors show onÀoff 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. SnS 2 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.
Nano Research, 2017
We demonstrated the controlled growth of two-dimensional (2D) hexagonal tin disulfide (SnS 2) nanoflakes with stacked monolayer atomic steps. The morphology was similar to flat-topped and step-sided mesa plateaus or step pyramids. The SnS 2 nanoflakes were grown on mica substrates via an atmospheric-pressure chemical vapor deposition process using tin monosulfide and sulfur powder as precursors. Atomic force microscopy (AFM), electron microscopy, and Raman characterizations were performed to investigate the structural features, and a sequential layer-wise epitaxial growth mechanism was revealed. In addition, systematic Raman characterizations were performed on individual SnS 2 nanoflakes with a wide range of thicknesses (1-100 nm), indicating that the A 1g peak intensity and Raman shifts were closely related to the thickness of the SnS 2 nanoflakes. Moreover, photoconductive AFM was performed on the monolayer-stepped SnS 2 nanoflakes, revealing that the flat surface and the edges of the SnS 2 atomic steps had different electrical conductive properties and photoconductive behaviors. This is ascribed to the dangling bonds and defects at the atomic step edges, which caused a height difference of the Schottky barriers formed at the interfaces between the PtIr-coated AFM tip and the step edges or the flat surface of the SnS 2 nanoflakes. The 2D SnS 2 crystals with regular monolayer atomic steps and fast photoresponsivity are promising for novel applications in photodetectors and integrated optoelectronic circuits.
Characteristics of layered tin disulfide deposited by atomic layer deposition with H2S annealing
AIP Advances, 2017
Tin disulfide (SnS2) has attracted much attention as a two-dimensional (2D) material. A high-quality, low-temperature process for producing 2D materials is required for future electronic devices. Here, we investigate tin disulfide (SnS2) layers deposited via atomic layer deposition (ALD) using tetrakis(dimethylamino)tin (TDMASn) as a Sn precursor and H2S gas as a sulfur source at low temperature (150° C). The crystallinity of SnS2 was improved by H2S gas annealing. We carried out H2S gas annealing at various conditions (250° C, 300° C, 350° C, and using a three-step method). Angle-resolved X-ray photoelectron spectroscopy (ARXPS) results revealed the valence state corresponding to Sn4+ and S2- in the SnS2 annealed with H2S gas. The SnS2 annealed with H2S gas had a hexagonal structure, as measured via X-ray diffraction (XRD) and the clearly out-of-plane (A1g) mode in Raman spectroscopy. The crystallinity of SnS2 was improved after H2S annealing and was confirmed using the XRD full-wi...
Physical Review Materials, 2020
The effects of Sn 5s lone pairs in the different phases of Sn sulphides are investigated with photoreflectance, hard x-ray photoemission spectroscopy (HAXPES) and density functional theory. Due to the photon energy-dependence of the photoionisation cross-sections, at high photon energy, the Sn 5s orbital photoemission has increased intensity relative to that from other orbitals. This enables the Sn 5s state contribution at the top of the valence band in the different Sn-sulphides, SnS, Sn 2 S 3 , and SnS 2 , to be clearly identified. SnS and Sn 2 S 3 contain Sn(II) cations and the corresponding Sn 5s lone pairs are at the valence band maximum (VBM), leading to ∼1.0-1.3 eV band gaps and relatively high VBM on an absolute energy scale. In contrast, SnS 2 only contains Sn(IV) cations, no filled lone pairs and therefore has a ∼2.3 eV room temperature band gap and much lower VBM compared with SnS and Sn 2 S 3. The direct band gaps of these materials at 20 K are found using photoreflectance to be 1.36, 1.08 and 2.47 eV for SnS, Sn2S3 and SnS2, respectively, which further highlights the effect of having the lone pair states at the VBM. As well as elucidating the role of the Sn 5s lone pairs in determining the band gaps and band alignments of the family of Sn-sulphide compounds, this also highlights how HAXPES is an ideal method for probing the lone pair contribution to the density of states of the emerging class of materials with ns 2 configuration.
2D SnS2 Nanostructure-Derived Photocatalytic Degradation of Organic Pollutants Under Visible Light
Frontiers in Nanotechnology
Wastewater produced by the textile industry contains various dyes and organic compounds that directly or indirectly affect surface water or groundwater pollution. Visible-light-driven semiconductor photocatalysis is the leading pathway for the degradation of environmental pollutants. Herein we report the bottom-up hydrothermal growth of 2D tin disulfide nanostructures (SnS2 NSs) for the efficient photodegradation of organic pollutants such as Rhodamine B (Rh.B) and Methyl Violet (M.V) in an aqueous medium under visible light (λ > 400 nm) irradiation. The as-synthesized SnS2 NSs were characterized by various structural, morphological, and optical techniques such as XRD, RAMAN, TEM, UV–Vis, Brunauer–Emmett–Teller, etc. Furthermore, the low bandgap (∼1.6 eV), the high surface area (56 m2/g), and the anionic nature of SnS2 NSs attribute to it as an efficient photocatalyst for photocatalytic applications. The photocatalytic properties of SnS2 NSs showed good degradation efficiency of ...
Tuning the Electronic Structure of Tin Sulfides Grown by Atomic Layer Deposition
ACS Applied Materials & Interfaces, 2013
In this study, tin sulfide thin films were obtained by atomic layer deposition (ALD) using Tetrakis(dimethylamino)tin (TDMASn, [(CH 3) 2 N] 4 Sn) and hydrogen sulfide (H 2 S). The growth rate of the tin sulfides (SnS x) was shown to be highly dependent on the deposition temperature, and reaction times of 1 second for the TDMASn and H 2 S were required to reach the saturation regime. Surface morphologies were smooth or rectangular with rounded corners as observed by a field emission scanning electron microscope (FE-SEM) and were dependent on temperature. X-ray diffraction results confirmed that the crystal structure of SnS x can be tuned by changing the ALD temperature. Below 120°C, SnS x films appeared to be amorphous. In addition, SnS x films were SnS 2 hexagonal at 140 and 150°C and SnS orthorhombic above 160°C. Similarly, the values of the optical band gap and binding energy showed significant differences between 150 and 160°C. The electronic structures of SnS x were extracted by UPS and absorption spectroscopy, and the unsaturated Sn 3d molecular orbital (MO) states in the band edge were found to be responsible for the great improvement in electrical conductivity. This study shows that TDMASn-H 2 S ALD is an effective deposition method for SnS x films, offering a simple approach to tune the physical properties.