Diffusion thermopower in graphene

摘要

The diffusion thermopower of graphene, S_d, is studied for 30 < T < 300 K, considering the electrons to be scattered by impurities, vacancies, surface roughness and acoustic and optical phonons via deformation potential couplings. S_d is found to increase almost linearly with temperature, determined mainly by vacancy and impurity scatterings. A departure from linear behaviour due to optical phonons is noticed. As a function of carrier concentration, a change in the sign of |S_d| is observed. Our analysis of recent thermopower data obtains a good fit. The limitations of Mott formula are discussed. Detailed analysis of data will enable a better understanding of the scattering mechanisms operative in graphene.