激子
单层
飞秒
材料科学
超快激光光谱学
超短脉冲
比克西顿
激发
分子物理学
吸收(声学)
光子学
显微镜
光电子学
光学
凝聚态物理
纳米技术
化学
物理
激光器
复合材料
量子力学
作者
Qiannan Cui,Frank Ceballos,Nardeep Kumar,Hui Zhao
出处
期刊:ACS Nano
[American Chemical Society]
日期:2014-02-24
卷期号:8 (3): 2970-2976
被引量:176
摘要
We present an experimental investigation on the exciton dynamics of monolayer and bulk WSe2 samples, both of which are studied by femtosecond transient absorption microscopy. Under the excitation of a 405 nm pump pulse, the differential reflection signal of a probe pulse (tuned to the A-exciton resonance) reaches a peak rapidly that indicates an ultrafast formation process of excitons. By resolving the differential reflection signal in both time and space, we directly determine the exciton lifetimes of 18 ± 1 and 160 ± 10 ps and the exciton diffusion coefficients of 15 ± 5 and 9 ± 3 cm2/s in the monolayer and bulk samples, respectively. From these values, we deduce other parameters characterizing the exciton dynamics such as the diffusion length, the mobility, the mean free path, and the mean free length. These fundamental parameters are useful for understanding the excitons in monolayer and bulk WSe2 and are important for applications in optoelectronics, photonics, and electronics.
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