Point defects in 2D materials block in-plane charge transport, which incurs negative effects on the photoresponse of 2D monolayer materials. In contrast to in-plane charge transport, we show that out-of-plane charge transport in 2D materials can be enhanced through controllable formation of point defects, thus enhancing the photoresponse of a vertical heterostructure. Graphene and WSe₂ monolayers were stacked together to construct a vertical heterostructure (W/G). Se point defects were artificially formed on the top atomic layer of WSe₂ with controllable density via Ga ion irradiation. The interlayer charge transport in the W/G heterostructure was detected with femtosecond optical probe–pump measurements and photoelectric detection. Our experiments show that point defects can be used to provide higher transfer rate for out-of-plane charge transport and more electronic states for photoexcitation, leading to enhanced photoinduced interlayer charge transfer from WSe₂ to graphene. Based on this feature, a photodetector based on W/G modified by point defects is proposed and implemented, exhibiting a fast photoresponsivity (∼0.6 ms) (2 orders of magnitude larger than the photoresponse in pristine W/G). This work demonstrates that out-of-plane charge transport is enhanced by the presence of point defects and illustrates an efficient method to optimize the performance of photoelectric devices based on vertical heterostructures.

中文翻译：

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使用点缺陷增强垂直堆叠二维异质结构中的平面外电荷传输

2D材料中的点缺陷会阻止面内电荷传输，从而对2D单层材料的光响应产生负面影响。与平面内电荷传输相反，我们表明可以通过可控地形成点缺陷来增强2D材料中的平面外电荷传输，从而增强垂直异质结构的光响应。石墨烯和WSe ₂单层堆叠在一起以构建垂直异质结构（W / G）。通过WSe ₂的顶部原子层通过可控的密度人工形成Se点缺陷镓离子辐照。W / G异质结构中的层间电荷传输通过飞秒光学探针-泵测量和光电检测来检测。我们的实验表明，点缺陷可用于为平面外电荷传输提供更高的传输速率，并为光激发提供更多的电子态，从而导致增强的WSe ₂诱导的光诱导层间电荷传输石墨烯。基于此特征，提出并实现了一种基于W / G的光电探测器，该探测器经点缺陷修正后具有快速的光响应能力（约0.6 ms）（比原始W / G的光响应大2个数量级）。这项工作表明点缺陷的存在增强了平面外电荷传输，并说明了一种基于垂直异质结构优化光电器件性能的有效方法。