CC BY
25LD-PS-3
Laser-induced modifications of optical properties in molybdenum disulfide covered by bismuth telluride
H. Rho1, T. Lee1, J.H. Ahn2
1Chonbuk National University, Department of Physics, Jeonju, Korea Republic of
2Korea Maritime and Ocean University, Department of Electronic Material Engineering, Busan,
Korea Republic of
Two-dimensional (2D) van der Waals heterostructures have attracted a great deal of attention due to their potential applications for novel 2D photonic and electronic nanodevices. Here, we report the effect of laser irradiation on the optical phonons and excitons in monolayer molybdenum disulfide (MoS2) covered by topological insulator bismuth telluride (Bi2Te3).
The Bi2Te3/MoS2 heterostructure was grown using chemical vapor deposition. When the incident laser power was weak, scattered signals from the monolayer MoS2 underneath the Bi2Te3 film were not detected owing to the strong absorption of incident laser light by Bi2Te3. However, when the Bi2Te3 film was exposed to a moderate excitation laser power, the optical phonons of the MoS2 layer were detected at 384 and 405 cm-1, corresponding to the in-plane £2g1 and the out-of-plane A1g phonon modes, respectively. To investigate the effect of the laser irradiation on the Bi2Te3/MoS2 heterostructure in detail, a sample surface was scanned using visible laser light with a moderate power. Interestingly, the color of the scanned region was changed, indicating that a structural change was occurred in the Bi2Te3 film under laser irradiation. Excitation laser-power
dependent Raman measurements showed that the ^s phonon was varied in energy with
increasing the laser power while the phonon did not show any variation in its energy, suggesting that a charge density in MoS2 was changed. Furthermore, laser-power dependent photoluminescence measurements showed also a variation in the A exciton peak energy. The correlated photoluminescence and Raman scattering results suggested that charge transfer occurred in the vertically stacked Bi2Te3/MoS2 heterostructure.
Acknowledgment: This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (Grant No. 2016R1D1A1B03935270).
