Nature of the Thermoelectric Power in Bipolar Semiconductors

Abstract

Thermoelectricity increasingly draws the attention of researchers because it can provide us with methods to generate environmentally clean energy and solid-state cooling. However, some problems in thermoelectricity’s physics remain unsolved. In this paper, a new approach to thermoelectric phenomena is presented, one that uses a linear description of the nonequilibrium charge carrier transport. The role of nonequilibrium carriers of both surface and bulk recombination processes has been shown to be crucial even within the linear approximation. Electron and hole quasi-Fermi levels originated from the thermal field are explicitly obtained in the case of a thermoelectric current flowing through an external circuit; the necessary corresponding boundary conditions are obtained. For the first time, it is shown that the quasi-Fermi level of one of the carriers can be a nonmonotonous function of spatial coordinates. General expressions for the thermoelectric current, the thermo-electromotive force (thermo-emf), and the electrical resistance of bipolar semiconductors have been obtained. Also for the first time, the influence of both surface recombination and surface resistance in thermoelectric phenomena was taken into account.