Liu Hsiang-Lin, Guo Huaihong, Yang Teng, Zhang Zhidong, Kumamoto Yasuaki, Shen Chih-Chiang, Hsu Yu-Te, Li Lain-Jong, Saito Riichiro, Kawata Satoshi
Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan.
Phys Chem Chem Phys. 2015 Jun 14;17(22):14561-8. doi: 10.1039/c5cp01347j.
We present a comprehensive Raman scattering study of monolayer MoS2 with increasing laser excitation energies ranging from the near-infrared to the deep-ultraviolet. The Raman scattering intensities from the second-order phonon modes are revealed to be enhanced anomalously by only the ultraviolet excitation wavelength 354 nm. We demonstrate theoretically that such resonant behavior arises from a strong optical absorption that forms near the Γ point and ½ΓK of the band structure and an inter-valley resonant electronic scattering by the M-point phonons. These results advance our understanding of the double resonance Raman scattering process in low-dimensional semiconducting nanomaterials and provide a foundation for the technological development of monolayer MoS2 in the ultraviolet frequency range.
我们展示了一项关于单层二硫化钼的全面拉曼散射研究，研究中激光激发能量不断增加，范围从近红外到深紫外。结果表明，仅在紫外激发波长354nm时，二阶声子模式的拉曼散射强度会异常增强。我们从理论上证明，这种共振行为源于在能带结构的Γ点和½ΓK附近形成的强光学吸收以及M点声子引起的谷间共振电子散射。这些结果增进了我们对低维半导体纳米材料中双共振拉曼散射过程的理解，并为单层二硫化钼在紫外频率范围内的技术发展奠定了基础。
