  We performed Scanning Thermal Microscopy measurements on single layers of
chemical-vapor-deposited -CVD- graphene supported by different substrates,
namely SiO2, Al2O3 and PET using a double-scan technique to remove the
contribution to the heat flux through the air and the cantilever. Then, by
adopting a simple lumped-elements model, we developed a new method that allows
determining, through a multi-step numerical analysis, the equivalent thermal
properties of thermally conductive coatings of nanometric thickness. In this
specific case we found that our CVD graphene is thermally equivalent, for heat
injection perpendicular to the graphene planes, to a coating material of
conductivity Keff=2.5+-0.3 mK and thickness teff=3.5+-0.3 nm in perfect contact
with the substrate. For the SiO2 substrate, we also measured stacks made of 2
and 4 CVD monolayers and we found that the effective thermal conductivity
increases with increasing number of layers and, with a technologically
achievable number of layers, is expected to be comparable to that of one order
of magnitude-thicker metallic thin films. This study provides a powerful method
for characterizing the thermal properties of graphene in view of several
thermal management applications.
