Crossover from ballistic to diffusive thermal transport in suspended graphene membranes

We report heat transport measurements on suspended single-layer graphene disks with radius of 150–1600 nm using a high-vacuum scanning thermal microscope. The results of this study revealed a radius-dependent thermal contact resistance between tip and graphene, with values between 1.15 and 1.52 × 108 KW−1. The observed scaling of thermal resistance with radius is interpreted in terms of ballistic phonon transport in suspended graphene discs with...