Remote processes

This chapter discusses remote processes that influence electron transport and manifest themselves in a variety of properties of interest. Coulomb and phonon-based interactions have appeared in many discussions in the text. Coulomb interactions can be short range or long range, but phonons have been treated as a local effect. At the nanoscale, the remote aspects of these interactions can become significant. An off-equilibrium distribution of phonons, in the limit of low scattering, will lead to the breakdown of the local description of phonon-electron coupling. Phonons can drag electrons, and electrons can drag phonons. Soft phonons—high permittivity—can cause stronger electron-electron interactions. So, plasmon scattering can become significant. Remote phonon scattering too becomes important. These and other such changes are discussed, together with phonon drag’s consequences for the Seebeck effect, as illustrated through the coupled Boltzmann transport equation. The importance of the zT coefficient for characterizing thermoelectric capabilities is stressed.