Wang Yu-Ting, Luo Chih-Wei, Yabushita Atsushi, Wu Kaung-Hsiung, Kobayashi Takayoshi, Chen Chang-Hsiao, Li Lain-Jong
Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan.
1] Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan [2] Taiwan Consortium of Emergent Crystalline Materials, Ministry of Science and Technology, Taipei 10601, Taiwan.
Sci Rep. 2015 Feb 6;5:8289. doi: 10.1038/srep08289.
The inherent valley-contrasting optical selection rules for interband transitions at the K and K' valleys in monolayer MoS2 have attracted extensive interest. Carriers in these two valleys can be selectively excited by circularly polarized optical fields. The comprehensive dynamics of spin valley coupled polarization and polarized exciton are completely resolved in this work. Here, we present a systematic study of the ultrafast dynamics of monolayer MoS2 including spin randomization, exciton dissociation, free carrier relaxation, and electron-hole recombination by helicity- and photon energy-resolved transient spectroscopy. The time constants for these processes are 60 fs, 1 ps, 25 ps, and ~300 ps, respectively. The ultrafast dynamics of spin polarization, valley population, and exciton dissociation provides the desired information about the mechanism of radiationless transitions in various applications of 2D transition metal dichalcogenides. For example, spin valley coupled polarization provides a promising way to build optically selective-driven ultrafast valleytronics at room temperature. Therefore, a full understanding of the ultrafast dynamics in MoS2 is expected to provide important fundamental and technological perspectives.
单层二硫化钼中K和K'谷间带间跃迁固有的谷对比度光学选择规则引起了广泛关注。这两个谷中的载流子可以被圆偏振光场选择性激发。在这项工作中，自旋谷耦合极化和极化激子的综合动力学得到了全面解析。在此，我们通过螺旋度和光子能量分辨瞬态光谱对单层二硫化钼的超快动力学进行了系统研究，包括自旋随机化、激子解离、自由载流子弛豫和电子 - 空穴复合。这些过程的时间常数分别为60飞秒、1皮秒、25皮秒和约300皮秒。自旋极化、谷布居和激子解离的超快动力学为二维过渡金属二卤化物各种应用中的无辐射跃迁机制提供了所需信息。例如，自旋谷耦合极化提供了一种在室温下构建光学选择性驱动超快谷电子学的有前景的方法。因此，全面理解二硫化钼中的超快动力学有望提供重要的基础和技术视角。
