Phonon drag in disordered films and structures

Abstract

Employing the quantum transport equation, we investigate the effect of electronic disorder on the phonon-drag thermopower. We consider the electron–phonon interaction via the deformation potential, which is strongly renormalized due to elastic electron scattering. The scattering potential of impurities, boundaries and defects is modeled by quasistatic scatterers and vibrating scatterers, which move in the same way as host atoms. In thin films, micro and nanostructures of the phonons relax mainly in a substrate, and the phonon-drag thermopower substantially depends on the character of electron scatterers. Vibrating scatterers decrease thermopower, while quasistatic scatterers (e.g. rigid boundaries) increase it. These changes in thermopower correlate to the disorder-induced modification of the electron–phonon relaxation rate.