Kavli Affiliate: Toeno Van Der Sar
| First 5 Authors: Kaj Dockx, Michele Buscema, Saravana Kumar, Tijmen van Ree, Abbas Mohtashami
| Summary:
The global electronic properties of solid-state devices are strongly affected
by the microscopic spatial paths of charge carriers. Visualising these paths in
novel devices produced by scalable processes would provide a quality assessment
method that can propel the device performance metrics towards commercial use.
Here, we use high-resolution nitrogen-vacancy (NV) magnetometry to visualise
the charge flow in gold-contacted, single-layer graphene devices produced by
scalable methods. Modulating the majority carrier type via field effect reveals
a strong asymmetry between the spatial current distributions in the electron
and hole regimes that we attribute to an inhomogeneous microscopic potential
landscape, inaccessible to conventional measurement techniques. In addition, we
observe large, unexpected, differences in charge flow through nominally
identical gold-graphene contacts. Moreover, we find that the current transfer
into the graphene occurs several microns before the metal contact edge. Our
findings establish high-resolution NV-magnetometry as a key tool for
characterizing scalable 2D material based devices, uncovering quality deficits
of the material, substrate, and electrical contacts that are invisible to
conventional methods.
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