Electron-phonon cooling in large monolayer graphene devices

We present thermal measurements of large-area (over 1000 μm2) monolayer graphene samples at cryogenic temperatures to study the electron-phonon thermal conductivity of graphene. By using two large samples with areas which differ by a factor of 10, we are able to clearly show the area dependence of the electron-phonon cooling. We find that, at temperatures far below the Bloch-Grüneisen temperature TBG, the electron-phonon cooling power is accurately described by the T 4 temperature dependence predicted for clean samples. Using this model, we are able to extract a value for the electron-phonon coupling constant as a function of gate voltage and the graphene electron-lattice deformation potential.