Temperature dependence of the relaxation time in scattering of elementary excitations in graphene

Abstract

This work primarily analyses the temperature dependence of the relaxation time of elementary excitations – quasi-particles (electrons) in graphene. Various mechanisms of relaxation (electrons collisions with impurities, with phonons, with vacancies, etc.) are essential in transport processes. Therefore, for some of the most characteristic and most common collisions a relaxation time is obtained. Regardless of which method (for example, solving the Boltzmann equation with the adequate initial boundary conditions and similar) is used for studying the transport characteristics, these relaxation times play a fundamental role. Their role is particularly significant in obtaining the temperature dependence of coefficients of electronic and thermal conductivity, as measurable macroscopic transport characteristics. In this text, relaxation times have been obtained by analytical analysis of the scattering process in the characteristic processes mentioned above. However, the temperature dependence of the relaxation time, including the relevant transport values, is not possible to obtain without the adequate law of scattering of elementary excitations. Here in this work, it was obtained by the method of Green's functions and it was applied to determine the temperature dependence of the relaxation time of charge carriers in the main scattering processes in graphene.