Ternary SnS(2-x)Se(x) Alloys Nanosheets and Nanosheet Assemblies with Tunable Chemical Compositions and Band Gaps for Photodetector Applications.

Jing Yu,Xiao-Shuang Chen,Yang Li,Liang Zhen,Cheng-Yan Xu,Fei Zhou,Ping-An Hu

doi:10.1038/srep17109

Jing Yu, Xiao-Shuang Chen + Show 5 more

Open Access

https://doi.org/10.1038/srep17109

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Journal: Scientific reports	Publication Date: Nov 30, 2015
Citations: 57	License type: CC BY 4.0

Affiliation: Harbin Institute of Technology

Abstract

Ternary metal dichalcogenides alloys exhibit compositionally tunable optical properties and electronic structure, and therefore, band gap engineering by controllable doping would provide a powerful approach to promote their physical and chemical properties. Herein we obtained ternary SnS2−xSex alloys with tunable chemical compositions and optical properties via a simple one-step solvothermal process. Raman scattering and UV-vis-NIR absorption spectra reveal the composition-related optical features, and the band gaps can be discretely modulated from 2.23 to 1.29 eV with the increase of Se content. The variation tendency of band gap was also confirmed by first-principles calculations. The change of composition results in the difference of crystal structure as well as morphology for SnS2−xSex solid solution, namely, nanosheets assemblies or nanosheet. The photoelectrochemical measurements indicate that the performance of ternary SnS2−xSex alloys depends on their band structures and morphology characteristics. Furthermore, SnS2−xSex photodetectors present high photoresponsivity with a maximum of 35 mA W−1 and good light stability in a wide range of spectral response from ultraviolet to visible light, which renders them promising candidates for a variety of optoelectronic applications.

Highlights

Ternary metal dichalcogenides alloys exhibit compositionally tunable optical properties and electronic structure, and band gap engineering by controllable doping would provide a powerful approach to promote their physical and chemical properties
Previous works about 2D MSSe are mainly focusing on chemical vapor deposition (CVD) growth[24,25,26], there have been only a few works on controlled synthesis of MSxSey alloys based on solution approach, which provides a efficient method for large-scale preparation and promising application
The main peak positions of SnS2−xSex alloys gradually shift toward lower angles with increasing Se content (Fig. 1b), indicating the increase of lattice constants and formation of solid solution rather than the mechanical mixture of two pure phases[27,28]

Summary

Introduction

Ternary metal dichalcogenides alloys exhibit compositionally tunable optical properties and electronic structure, and band gap engineering by controllable doping would provide a powerful approach to promote their physical and chemical properties. In view of the similar atomic structure of congeners, it is possible to construct a mixed alloy system (MSSe, M is metal atom) with tunable composition and continuously tuned band gap, which has been widely studied for applications in nanoelectronics and nanophotonics[10,11,12,13]. Theoretical calculations have proved that mixing energy of transition metal dichalcogenides (TMDs) ternary alloys is low and mixed MoS2/MoSe2/MoTe2 compounds are thermodynamically stable at room temperature Their compositions and band gaps could be continuously tuned between the constituent limits, indicating the benefit of band gap engineering for optoelectronic applications[16]. The photoresponsivity of SnS0.44Se1.56 films was found to be strongly dependent on incident light power and wavelength

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Conclusion