Bi2Se3/MoS2异质结的光学性质

Optical properties of Bi2Se3/MoS2 heterojunction

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.

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 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.