Current Saturation and Surface Polar Phonon Scattering in Graphene

We present a study of transport in graphene devices on polar insulating substrates using a tight-binding model. The mobility is computed using a multiband Boltzmann treatment. We provide the scaling of the surface polar phonon contribution to the low-field mobility with carrier density, temperature, and distance from the substrate. At high bias, we find that graphene self-heating effect is essential to account for the observed saturated current behavior. We predict that by optimizing the device cooling, the high bias currents can be significantly enhanced.