Ultrafast dynamics of bright and dark positive trions for valley polarization in monolayer WSe2
Ultrafast dynamics of bright and dark positive trions for valley polarization in monolayer WSe2
复制标题
DOI：
10.1103/physrevb.99.245307
复制
发表时间：
2019-06
影响因子：
3.7
通讯作者：
K. Shinokita;Xiaofan Wang;Y. Miyauchi;Kenji Watanabe;T. Taniguchi;S. Konabe;K. Matsuda
中科院分区：
文献类型：
--
作者：
K. Shinokita;Xiaofan Wang;Y. Miyauchi;Kenji Watanabe;T. Taniguchi;S. Konabe;K. Matsuda
利用时间分辨和偏振分辨光致发光以及泵浦-探测光谱研究了单层（1 L-）WSe 2中亮、暗带正电荷激子（正激子）的光激发态动力学.在10 K时，亮正三电子向暗正三电子（10±5 ps）和基态（10± 1 ps）的弛豫速度较快，而暗正三电子向基态（10 ± 300 ps）的弛豫速度较慢。在圆偏振光的谷选择激发下，10 K时亮激子的谷弛豫时间为1.5±0.5 ns，比典型的激子谷弛豫时间10 ps长得多。这种见解的正trions的较慢的谷弛豫动力学表明，电子-空穴交换相互作用，是占主导地位的中性激子谷弛豫，抑制额外的空穴的存在。
Optical excited state dynamics of bright and dark positively charged excitons (positive trions) in 1-layer (1L-) WSe 2 were studied by a combination of time- and polarization-resolved photoluminescence and pump-probe spectroscopy. Bright positive trions showed ultrafast relaxation to dark positive trions ( ∼ 1 ps) and to ground state (10±5 ps), while dark positive trions showed slow decay to the ground state ( ∼ 300 ps) at 10 K. Under valley selective excitation with circularly polarized light, the valley relaxation time of the bright trions was 1.5±0.5 ns at 10 K, which is much longer than typical exciton valley relaxation times of 10 ps. This insight into the slower valley relaxation dynamics of positive trions suggests that the electron-hole exchange interactions that is dominant in neutral exciton valley relaxation, are suppressed by the presence of additional holes.