Raman Spectroscopy of Two-Dimensional Bi₂Te x Se3 - x Platelets Produced by Solvothermal Method

Jian Yuan; Meng Zhao; Wengzhi Yu; Yao Lu; Caiyun Chen; Meng Xu; Shaojuan Li; Kian Ping Loh; QiaoliangBao

doi:10.3390/ma8085007

Raman Spectroscopy of Two-Dimensional Bi₂Te _x Se_{3 - x} Platelets Produced by Solvothermal Method

Materials (Basel). 2015 Aug 5;8(8):5007-5017. doi: 10.3390/ma8085007.

Authors

Jian Yuan¹, Meng Zhao², Wengzhi Yu³, Yao Lu⁴, Caiyun Chen⁵, Meng Xu⁶, Shaojuan Li⁷, Kian Ping Loh⁸; QiaoliangBao^{9

10}

Affiliations

¹ Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, China. 20124214040@suda.edu.cn.
² Department of Chemistry, and Graphene Research Centre, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore. zhaomeng@nus.edu.sg.
³ Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, China. 20144214003@stu.suda.edu.cn.
⁴ Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, China. 20134214095@stu.suda.edu.cn.
⁵ Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, China. 20124214017@suda.edu.cn.
⁶ Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, China. xujane1225@gmail.com.
⁷ Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, China. sjli@suda.edu.cn.
⁸ Department of Chemistry, and Graphene Research Centre, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore. chmlohkp@nus.edu.sg.
⁹ Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123, China. qlbao@suda.edu.cn.
¹⁰ Department of Materials Science and Engineering, Monash University, Clayton, VIC 3800, Australia. qlbao@suda.edu.cn.

Abstract

In this paper, we report a facile solvothermal method to produce both binary and ternary compounds of bismuth chalcogenides in the form of Bi₂Te_xSe_{3 - x}. The crystal morphology in terms of geometry and thickness as well as the stoichiometric ratio can be well controlled, which offers the opportunities to systematically investigate the relationship between microstructure and phonon scattering by Raman spectroscopy. Raman spectra of four compounds, i.e., Bi₂Se₃, Bi₂Se₂Te, Bi₂SeTe₂ and Bi₂Te₃, were collected at four different excitation photon energies (2.54, 2.41, 1.96, and 1.58 eV). It is found that the vibrational modes are shifted to higher frequency with more Se incorporation towards the replacement of Te. The dependence of Raman vibrational modes on excitation photon energy was investigated. As the excitation photon energy increases, three Raman vibrational modes (A_1g¹, E_g² and A_1g²) of the as-produced compounds move to low frequency. Three Infrared-active (IR-active) modes were observed in thin topological insulators (TIs) crystals.

Keywords: Raman spectroscopy; bismuth chalcogenide; infrared active; solvothermal; stoichiometric ratio.