Electrical Characterization of Discrete Defects and Impact of Defect Density on Photoluminescence in Monolayer WS2.
Electrical Characterization of Discrete Defects and Impact of Defect Density on Photoluminescence in Monolayer WS2.
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DOI：
10.1021/acsnano.7b08566
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发表时间：
2018-01
期刊：
影响因子：
17.1
通讯作者：
M. Rosenberger;Hsun-Jen Chuang;K. McCreary;Connie H Li;B. Jonker
中科院分区：
文献类型：
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作者：
M. Rosenberger;Hsun-Jen Chuang;K. McCreary;Connie H Li;B. Jonker
过渡金属二硫属化合物（transition-metaldichalcogenides，TMD）是一类具有良好电学和光电性能的二维材料，具有广阔的应用前景。TMD的性能预计会受到生长过程和/或制造过程中产生的各种缺陷的强烈影响。尽管理解缺陷相关现象的重要性，仍然需要在大面积上对缺陷进行定量的纳米级表征，以便理解缺陷与观察到的特性（例如光致发光（PL）和电导率）之间的关系。在这项工作中，我们提出了导电原子力显微镜测量，揭示了纳米级的电子活性缺陷的化学气相沉积生长的WS 2单层的缺陷密度从2.3 × 1010 cm-2到4.5 × 1011 cm-2。将这些缺陷密度测量结果与大面积（>20 μm距离）的PL测量结果进行比较，发现WS 2 PL强度与缺陷密度之间存在很强的反比关系。我们提出了一个模型，其中所观察到的电子活性缺陷作为非辐射复合中心，并获得良好的实验和模型之间的协议。
Transition-metal dichalcogenides (TMDs) are an exciting class of 2D materials that exhibit many promising electronic and optoelectronic properties with potential for future device applications. The properties of TMDs are expected to be strongly influenced by a variety of defects which result from growth procedures and/or fabrication. Despite the importance of understanding defect-related phenomena, there remains a need for quantitative nanometer-scale characterization of defects over large areas in order to understand the relationship between defects and observed properties, such as photoluminescence (PL) and electrical conductivity. In this work, we present conductive atomic force microscopy measurements which reveal nanometer-scale electronically active defects in chemical vapor deposition-grown WS2 monolayers with defect density varying from 2.3 × 1010 cm-2 to 4.5 × 1011 cm-2. Comparing these defect density measurements with PL measurements across large areas (>20 μm distances) reveals a strong inverse relationship between WS2 PL intensity and defect density. We propose a model in which the observed electronically active defects serve as nonradiative recombination centers and obtain good agreement between the experiments and model.