  Ultrathin sheets of MoS2 are 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 MoS2 obtained 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 {\Delta}R while the
tip is raster scanned above the sample, an image of electron flow is obtained.
We present images of electron flow in an MoS2 device patterned into a hall bar
geometry. A three-layer MoS2 sheet 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 = 1.3x10^12 cm^-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 = 5.4x10^11 cm^-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.
