关键词: 二维材料, Bi₂Se₃, MoS₂, 异质结, 荧光光谱

Abstract: A monolayer MoS₂ and nano-thickness Bi₂Se₃ flakes were stacked to form heterostructures.Exciton luminescence, interface interaction and charge transfer in Bi₂Se₃/MoS₂ heterojunctions were studied deeply by the reflection, Raman and photoluminescence spectroscopy techniques under the HR-Evolution Raman spectroscopy system. First, the Bi₂Se₃ flakes with different thicknesses were transferred to a CVD-grown monolayer MoS₂ by a dry transfer technique to form Bi₂Se₃/MoS₂ heterostructures. Then, the reflection spectroscopy and Raman spectroscopy echniques were used to detect the uniformity and the interfacial- DOI:10.3969/j.issn.1000-1565.2020.03.004Bi₂Se₃/MoS₂异质结的光学性质刘燚¹,王龙龙¹,胡国锋²,刘雪璐³,武宏利¹,李晓莉¹(1. 河北大学 物理科学与技术学院,河北 保定 071002;2. 深圳大学 物理与光电工程学院,广东 深圳 518060;3. 中国科学院半导体研究所 半导体超晶格国家重点实验室,北京 100083)摘 要:对单层MoS₂与纳米级别厚度的Bi₂Se₃薄片进行组合构建超薄异质结,利用HR-Evolution显微共聚焦拉曼光谱系统,结合反射、拉曼和荧光光谱学测试技术,对Bi₂Se₃/MoS₂异质结中的激子发光、异质结中的界间相互作用和电荷转移等行为进行了深入而系统的研究.首先,利用干法转移技术将不同厚度的Bi₂Se₃薄片转移到CVD生长的单层MoS₂上构建Bi₂Se₃/MoS₂异质结.然后,利用反射光谱和拉曼光谱技术探测异质结的平整度和界面耦合质量,表明异质结的2种材料发生堆叠后具有良好的平整度,按照不同厚度对白光保留着良好的透光性;2种材料堆叠时没有引入附加应力,形成的异质结具有良好的界面耦合质量.最后,通过对异质结的荧光光谱研究发现下层母体材料MoS₂的A、B激子峰的发光效率大大减弱,同时它们的发光波长随着上层Bi₂Se₃薄片的厚度增加逐渐减小,半高宽随着上层Bi₂Se₃薄片的厚度增加逐渐变窄,这说明电子传递到Bi₂Se₃/MoS₂界面后发生退激发,使得MoS₂的发光发生明显猝灭,而且该结果可能还包括异质结的电子能带结构变化导致电荷发生重新分布的的更深层次原因.该研究对新型光电子器件的设计和应用具有一定的意义和指导作用.关键词:二维材料;Bi₂Se₃;MoS₂;异质结;荧光光谱中图分类号:O433.4 文献标志码:A 文章编号:1000-1565(2020)03-0249-06Optical properties of Bi₂Se₃/MoS₂ heterojunctionLIU Yi¹, WANG Longlong¹, HU Guofeng², LIU Xuelu³, WU Hongli¹, LI Xiaoli¹(1.College of Physics Science and Technology, Hebei University, Baoding 071002, China;2.College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China;3.The State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, CAS, Beijing 100083, China)Abstract: A monolayer MoS₂ and nano-thickness Bi₂Se₃ flakes were stacked to form heterostructures.Exciton luminescence, interface interaction and charge transfer in Bi₂Se₃/MoS₂ heterojunctions were studied deeply by the reflection, Raman and photoluminescence spectroscopy techniques under the HR-Evolution Raman spectroscopy system. First, the Bi₂Se₃ flakes with different thicknesses were transferred to a CVD-grown monolayer MoS₂ by a dry transfer technique to form Bi₂Se₃/MoS₂ heterostructures. Then, the reflection spectroscopy and Raman spectroscopy echniques were used to detect the uniformity and the interfacial- 收稿日期:2019-11-20 基金项目:国家自然科学基金青年科学基金项目(11504077);河北大学研究生创新资助项目(hbu2020ss077);河北大学研究生创新资助项目(hbu2019ss033);河北大学大学生创新资助项目(2019150). 第一作者:刘燚(1996—),男,福建泉州人,河北大学在读硕士研究生,主要从事半导体光学方面的研究.E-mail: 20181438@stumail.hbu.edu.cn 通信作者:李晓莉(1982—),女,河北南宫人,河北大学副教授,博士,主要从事半导体光学方面的研究.E-mail: xiaolili@hbu.edu.cn第3期刘燚等:Bi₂Se₃/MoS₂异质结的光学性质coupling quality ofheterojunctions, and it was proved that the two materials in the heterostructures had good uniformity after stacking and had excellent white light transmittance with different thicknesses, and no additional strains were introduced when heterostructures were formed to ensure a good interface coupling quality. Finally, the photoluminescence spectra of heterostructures were probed. It is interesting to note that the luminescence efficiency of the A and B exciton peaks from MoS₂ in the bottom was sharply reduced, their peak position downshifted with the increase of the thickness of Bi₂Se₃ flakes at the top, and their full width at half maximum(FWHM)gradually narrowed when the thickness of Bi₂Se₃ flakes increased. It indicated that the electrons were transferred to the interface of Bi₂Se₃/MoS₂ and then de-excited, which caused the photoluminescence of MoS₂ to be quenched. Moreover, the results suggested that the charges were likely to be redistributed due to electron band structure renormalization in the heterostructures. This study has a certain significance and guidance for the design and application of new optoelectronic devices.

Key words: 2D material, Bi₂Se₃, MoS₂, heterojunction, fluorescence spectrum