Research On Preparation And Properties Of TIN Sulfide Powders And Thin Films

Stannum sulfide （SnS） is an important II-VI semiconductor with awide-band gap ranging from1.0to1.5eV. SnS has appropriate electrical featuresfor use in solar cells. SnS can be potentially used as solar absorber in a thin filmsolar cell and near-infrared detector, and as photovoltaic materials.SnS powders were prepared by microwave hydrothermal method, the SnSfilms were synthesized by liquid phase deposition. The phase compositions，morphologies and optical properties of the as-prepared powder and thin filmswere characterized by X-ray diffraction （XRD）, Scanning electron microscope（SEM）, Field emission scanning electron microscope （FE-SEM）, Energydispersive X-ray spectroscopy （EDS）, Transmission electron microscopy （TEM）,UV/Visible/near-infrared spectroscopy （UV-VIS-NIR） and Photoluminescence（PL）. The influence of different sulfur sources, microwave hydrothermaltemperatures, microwave hydrothermal times, the molar ratios of S/Sn, the pHvalues of precursor solution on the phase compositions, morphologies andoptical properties of the SnS powder and thin films were investigated. SnScrystallites with Quasi-spheres nanostructures, irregular cuboid and flowerclusters structure were prepared by microwave hydrothermal process. And theSnS thin films were prepared by liquid phase deposition.SnS powders were synthesized by a microwave hydrothermal process usingSnCl₂·2H₂O as Sn source and （NH4）2S, SC（NH₂）₂, CH₃CSNH₂, Na₂S₂O₃as Ssource under the same reaction condition. The influence of differnent S source onthe crystallization, morphology and optical property of SnS crystallity wereinvestigated. Results indicate that the as-prepared products are orthorhombicstructure SnS except the S source of Na₂S₂O₃. The morphology of SnS powdersexhibits quasi-spheres, irregular cuboid and flower clusters structure underdifferent S source. UV-Visible spectral analysis shows that the optical band gapof the as-prepared products is about1.48eV¹.61eV. Photoluminescence spectrum measured at room temperature shows near-infrared emission at830nm.SnS crystallites were prepared by the microwave hydrothermal（M-H）process with the SnCl₂·2H₂O as Sn source and （NH4）2S as S source. Resultsindicate that the prepared SnS crystallites are mostly poly-crystalline withorthorhombic structure, and grain shape is nearly spherical. With the increase ofreaction temperature, the crystalline sizes are increased from20nm to50nm. Asprolonging of reaction time, the grain size is increased. The contents andmorphology of the products were affected by the S/Sn molar ratio. Whenincreasing the S/Sn molar ratio, the composition of the products changed frompure SnS to the mixture of SnS and SnS₂, and the morphologies transformedfrom quasi-spheres to sheet-assemble spheres like shape. A near-infraredphotoluminescence （PL） emissiom at room temperature was verified for the SnSpowders when exited by551nm wavelength. By UV-visible spectroscopyanalysis, the optical band gap of SnS nanocrystallites is about1.61eV.SnS powders were obtained by the microwave hydrothermal （M-H）systhesis technique using SnCl₂·2H₂O and CH₃CSNH₂as precursors. Bychanging the M-H processing temperature and time. SnS crystallites withdifferernt sizes and morphologies were be achieved. The results show that theoptimal synthetic conditions to obtain SnS microspheres when the microwavehydrothermal temperature is180°C, and hydrothermal time is30min. Flower-likenanosheets clusters of SnS were synthesized by the reactions SnCl₂·2H₂O andCH₃CSNH₂in the presence of CTAB through a microwave hydrothermal process.The results indicate that the as-prepared products were orthorhombic structure,the morphology of SnS powders was flower-like nanosheets clusters structure.UV-Visible spectroscopy analysis shows that the optical band gap of theas-prepared products is about1.51eV.The SnS films were obtained by liquid phase methods, and depositiontemperature were100℃and24h. Its microstructure is composed of nanospheres,and from AFM images, the thickness of SnS thin film prepared by liquid phasemethod was showed about100²00nm. The optical band gap of the as-preparedfilm is about1.37eV.