High quality graphene heterostructures are made by stacking successive layers of mechanically exfoliated hexagonal boron nitride and monolayer graphene. A reactive ion etch slices through the stack revealing the 1-dimensional edge of the graphene which is electrically contacted. In this way, our lab creates devices with room temperature electron and hole mobility of over 100,000 cm^2/Vs and low temperature mobility up to 1 million cm^2/Vs. High resistance samples are impedance matched using an on-chip LC tank circuit and our setup collects the microwave radiation emitted by the device. This radiation--known as Johnson noise-- is used to determine the local temperature of the electrons within the graphene. By applying a know heat load to the device we can monitor the temperature rise and measure the electronic component of graphene's thermal conductivity. Recently, we have demonstrated the first precision measurements of electronic thermal transport in boron nitride encapsulated graphene from 3 to 300 Kelvin.
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