Investigation of carrier migration from WS2 monolayer to substrate by photoluminescence
Investigation of carrier migration from WS2 monolayer to substrate by photoluminescence
复制标题
通过光致发光研究载流子从 WS2 单层到基底的迁移
DOI：
10.1016/j.jlumin.2021.118538
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发表时间：
2021-10
影响因子：
3.6
通讯作者：
Shijie Xu
中科院分区：
文献类型：
--
作者：
Qing Peng;Xiaotian Ge;Rongxin Wang;Ding Ding;Zhongmiao Gong;Changcheng Zheng;Jiqiang Ning;Ruiying Zhang;Shijie Xu
原子薄二维（2D）半导体（如ws2单层）中的载流子容易与周围环境相互作用，这可能对二维半导体的电学和光学性质产生重大影响。在SiO2/Si衬底上机械剥离的ws2单分子层中，观察到光致发光强度与激发功率密度的异常依赖关系，表现为在一定功率密度下激子和trion发射强度突然下降，然后强度增加缓慢。未剥落和湿润的ws2单分子层表现出相似的PL强度异常变化，但不同的功率密度会导致强度下降。PL强度的突然下降是由于在激光照射下，被捕获的空气或水与单层和基材的相互作用导致单层与基材的接触状态发生改变，从而改变了从单层到基材的载流子传输速率。建立了稳态下载流子复合和输运过程的速率方程模型，并证明了激子、三角子和自由电荷群对跨平面输运速率的变化依赖性，这一致地解释了PL强度对激发功率密度的异常依赖性。在这项工作中，载流子输运在PL性能中的重要作用得到了验证，并进一步了解了原子薄二维半导体中的载流子相互作用。
Carriers in atomically thin two-dimensional (2D) semiconductors like WS2monolayers are prone to interact with their surroundings, which may have a significant impact on both the electric and optical properties of 2D semiconductors. In this work, abnormal dependence of photoluminescence (PL) intensity on excitation power densities is observed in mechanically exfoliated WS2monolayers on SiO2/Si substrates, which is manifested as a sudden intensity drop of exciton and trion emissions at certain power density followed by much slowed intensity increase. As-exfoliated and wetted WS2monolayers exhibit similar abnormal variation of PL intensity but different power densities that trigger the intensity drop. The sudden drop of PL intensity is ascribed to the modification to the contact status of the monolayer with the substrate, caused by the interplay of the trapped air or water with the monolayer and the substrate upon laser irradiation, which therefore alters the carries transport rate from the monolayer to the substrate. A rate equation model has been developed to delicately deal with the carrier recombination and transport processes in a steady state, and the variation dependence of exciton, trion and free charge populations on the cross-plane transport rate is demonstrated, which consistently explains the abnormal PL intensity dependence on the excitation power density. The important role of carrier transport in the PL performance has been verified in this work, and further understanding of the carrier interactions in atomical thin 2D semiconductors has been achieved.
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DOI：
10.1038/s43586-022-00151-5
发表时间：
2014-03
期刊：
Nature Reviews Methods Primers
影响因子：
--
作者：
R. Gorbachev
通讯作者：
R. Gorbachev
影响因子：
5.7
作者：
van Bremen, Rik;Vonk, Kevin;Bampoulis, Pantelis
通讯作者：
Bampoulis, Pantelis
影响因子：
16.6
作者：
Rivera, Pasqual;Schaibley, John R.;Xu, Xiaodong
通讯作者：
Xu, Xiaodong
影响因子：
17.1
作者：
Bernardi, Marco;Palummo, Maurizia;Grossman, Jeffrey C.
通讯作者：
Grossman, Jeffrey C.
影响因子：
17.1
作者：
Ovchinnikov, Dmitry;Allain, Adrien;Kis, Andras
通讯作者：
Kis, Andras