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Energy-Resolved Photoconductivity Mapping in a Monolayer–Bilayer WSe2 Lateral Heterostructure
Nano Letters ( IF 9.6 ) Pub Date : 2018-10-05 00:00:00 , DOI: 10.1021/acs.nanolett.8b03318 Zhaodong Chu 1 , Ali Han 2 , Chao Lei 1 , Sergei Lopatin 3 , Peng Li 2 , David Wannlund 1 , Di Wu 1 , Kevin Herrera 1 , Xixiang Zhang 2 , Allan H. MacDonald 1 , Xiaoqin Li 1 , Lain-Jong Li 2 , Keji Lai 1
Nano Letters ( IF 9.6 ) Pub Date : 2018-10-05 00:00:00 , DOI: 10.1021/acs.nanolett.8b03318 Zhaodong Chu 1 , Ali Han 2 , Chao Lei 1 , Sergei Lopatin 3 , Peng Li 2 , David Wannlund 1 , Di Wu 1 , Kevin Herrera 1 , Xixiang Zhang 2 , Allan H. MacDonald 1 , Xiaoqin Li 1 , Lain-Jong Li 2 , Keji Lai 1
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Vertical and lateral heterostructures of van der Waals materials provide tremendous flexibility for band-structure engineering. Because electronic bands are sensitively affected by defects, strain, and interlayer coupling, the edge and heterojunction of these two-dimensional (2D) systems may exhibit novel physical properties, which can be fully revealed only by spatially resolved probes. Here, we report the spatial mapping of photoconductivity in a monolayer–bilayer WSe2 lateral heterostructure under multiple excitation lasers. As the photon energy increases, the light-induced conductivity detected by microwave impedance microscopy first appears along the heterointerface and bilayer edge, then along the monolayer edge, inside the bilayer area, and finally in the interior of the monolayer region. The sequential emergence of mobile carriers in different sections of the sample is consistent with the theoretical calculation of local energy gaps. Quantitative analysis of the microscopy and transport data also reveals the linear dependence of photoconductivity on the laser intensity and the influence of interlayer coupling on carrier recombination. Combining theoretical modeling, atomic-scale imaging, mesoscale impedance microscopy, and device-level characterization, our work suggests an exciting perspective for controlling the intrinsic band gap variation in 2D heterostructures down to a regime of a few nanometers.
中文翻译：
单层-双层WSe 2横向异质结构中的能量分辨光电导映射
范德华材料的垂直和横向异质结构为带结构工程提供了极大的灵活性。由于电子带易受缺陷，应变和层间耦合的影响，因此这些二维（2D）系统的边缘和异质结可能表现出新颖的物理特性，只有通过空间分辨的探针才能充分揭示这些特性。在这里，我们报告了单层-双层WSe 2中光电导的空间映射多个激发激光下的横向异质结构。随着光子能量的增加，由微波阻抗显微镜检测到的光导电导率首先出现在异质界面和双层边缘，然后沿着单层边缘出现在双层区域内部，最后出现在单层区域内部。样本不同部分中移动载波的连续出现与局部能隙的理论计算是一致的。显微镜和传输数据的定量分析还揭示了光电导率对激光强度的线性依赖性以及层间耦合对载流子复合的影响。结合了理论建模，原子级成像，中尺度阻抗显微镜和设备级表征，
更新日期：2018-10-05
中文翻译：
单层-双层WSe 2横向异质结构中的能量分辨光电导映射
范德华材料的垂直和横向异质结构为带结构工程提供了极大的灵活性。由于电子带易受缺陷，应变和层间耦合的影响，因此这些二维（2D）系统的边缘和异质结可能表现出新颖的物理特性，只有通过空间分辨的探针才能充分揭示这些特性。在这里，我们报告了单层-双层WSe 2中光电导的空间映射多个激发激光下的横向异质结构。随着光子能量的增加，由微波阻抗显微镜检测到的光导电导率首先出现在异质界面和双层边缘，然后沿着单层边缘出现在双层区域内部，最后出现在单层区域内部。样本不同部分中移动载波的连续出现与局部能隙的理论计算是一致的。显微镜和传输数据的定量分析还揭示了光电导率对激光强度的线性依赖性以及层间耦合对载流子复合的影响。结合了理论建模，原子级成像，中尺度阻抗显微镜和设备级表征，
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