Heat transport studies are a powerful tool to obtain information about both the
phononic and electronic properties of materials. Graphene is a two-dimensional
crystal (1-atom thick) where electrons behave relativistically, and which has
tremendous potential for short-term technological applications. We measure the
heat conductivity of graphene, and aim to gather fundamental information about
its phonon modes and their coupling to its Dirac fermions (electrons or holes). Our
measurements can also assess the potential of graphene for technological applications
such as heat management in nanodevices.
We report the first detailed measurements of heat conductivity, κ, and electron
mobility, of graphene versus temperature (6K - 350K) and charge density. We have
fabricated suspended graphene devices. Our suspended devices prevent any undesired
heat leakage and allow a simple modeling of the heat transport. We use these graphene
devices as their own heat sources (Joule heating) and thermometers (resistivity) to
measure their heat conductivity. We observe that thermal conductivity varies by 3
orders of magnitude as a function of temperature, indicating phonon heat transport,
and by more than an order of magnitude as a function of charge density, suggesting
that electron-phonon coupling is important. We observed κ up to 1500 W/m.K.