Role of temperature dependent scattering mechanisms on the electronic transport in freestanding graphene foams*

We present electronic transport properties of freestanding graphene foam (pristine and nitrogen-doped) using four-probe resistance (R) and Seebeck coefficient (S) measurements in the temperature range ~10-300 K. In pristine graphene, a low value of S ~2 μV/K at room temperature was measured which is attributed to the unique band structure of graphene (symmetric) and low density of states near the Dirac point. With nitrogen doping, the electron-hole symmetry was broken, leading to a six-fold enhancement of S. A theoretical study of temperature dependent scattering mechanisms contributing to the electronic transport characteristics was performed within the framework of Boltzmann transport theory under relaxation time approximation.