Department of Physics , The University of Texas at Austin , Austin , Texas 78712 , United States.
Microelectronics Research Center, Department of Electrical and Computer Engineering , The University of Texas at Austin , Austin , Texas 78758 , United States.
Nano Lett. 2019 Mar 13;19(3):1976-1981. doi: 10.1021/acs.nanolett.8b05159. Epub 2019 Feb 21.
The vertical stacking of van der Waals (vdW) materials introduces a new degree of freedom to the research of two-dimensional (2D) systems. The interlayer coupling strongly influences the band structure of the heterostructures, resulting in novel properties that can be utilized for electronic and optoelectronic applications. Based on microwave microscopy studies, we report quantitative electrical imaging on gated molybdenum disulfide (MoS)/tungsten diselenide (WSe) heterostructure devices, which exhibit an intriguing antiambipolar effect in their transfer characteristics. Interestingly, in the region with significant source-drain current, electrons in the n-type MoS and holes in the p-type WSe segments are nearly balanced, whereas the heterostructure area is depleted of mobile charges. The spatial evolution of local conductance can be ascribed to the lateral band bending and formation of depletion regions along the line of MoS-heterostructure-WSe. Our work vividly demonstrates the microscopic origin of novel transport behaviors, which is important for the vibrant field of vdW heterojunction research.
范德华（vdW）材料的垂直堆叠为二维（2D）系统的研究带来了新的自由度。层间耦合强烈影响异质结构的能带结构，从而产生可用于电子和光电子应用的新颖特性。基于微波显微镜研究，我们报告了在门控二硫化钼（MoS）/二硒化钨（WSe）异质结构器件上进行的定量电成像，其在传输特性中表现出有趣的反双极效应。有趣的是，在源漏电流显著的区域中，n 型 MoS 中的电子和 p 型 WSe 段中的空穴几乎平衡，而异质结构区域中没有可移动电荷。局部电导的空间演化可归因于沿 MoS-异质结构-WSe 线的横向能带弯曲和耗尽区的形成。我们的工作生动地展示了新的传输行为的微观起源，这对于范德华异质结研究这一充满活力的领域非常重要。
