Imaging Electron Motion in a Few Layer MoS2 Device

33rd International Conference on the Physics of Semiconductors

Bhandari, S.^1 ; Wang, K.^2 ; Watanabe, K.^3 ; Taniguchi, T.^3 ; Kim, P.^1,2 ; Westervelt, R.M.^1,2

School of Engineering and Applied Sciences, Harvard University, Cambridge

MA

02138, United States^1

Department of Physics, Harvard University, U.S.A, Cambridge

MA

02138, United States^2

National Institute for Materials Science, 1-1 Naniki, Tsukuba

305-0044, Japan^3

关键词: Electron motion;    Electron trajectories;    GaAs/AlGaAs heterostructures;    Image charges;    Multilayer graphene;    Sample surface;    Scanned probe;    Ultrathin sheets;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/864/1/012031/pdf
DOI  :  10.1088/1742-6596/864/1/012031

来源: IOP

【 摘 要 】

Ultrathin sheets of MoS2are a newly discovered 2D semiconductor that holds great promise for nanoelectronics. Understanding the pattern of current flow will be crucial for developing devices. In this talk, we present images of current flow in MoS2obtained with a Scanned Probe Microscope (SPM) cooled to 4 K. We previously used this technique to image electron trajectories in GaAs/AlGaAs heterostructures and graphene. The charged SPM tip is held just above the sample surface, creating an image charge inside the device that scatters electrons. By measuring the change in resistance ΔR while the tip is raster scanned above the sample, an image of electron flow is obtained. We present images of electron flow in an MoS2device patterned into a hall bar geometry. A three-layer MoS2sheet is encased by two hBN layers, top and bottom, and patterned into a hall-bar with multilayer graphene contacts. An SPM image shows the current flow pattern from the wide contact at the end of the device for a Hall density n = 1.3×1012cm-2. The SPM tip tends to block flow, increasing the resistance R. The pattern of flow was also imaged for a narrow side contact on the sample. At density n = 5.4×1011cm-2; the pattern seen in the SPM image is similar to the wide contact. The ability to image electron flow promises to be very useful for the development of ultrathin devices from new 2D materials.