Diffusion thermopower of the two-dimensional electron gas in AlP quantum wells including exchange and correlation effects

We investigate the diffusion thermopower for the quasi-two-dimensional electron gas in a GaP/AlP/GaP quantum well taking into account exchange and correlation effects. We consider the interface-roughness and remote impurity scattering, and study the dependence of diffusion thermopower on the temperature, carrier density and quantum well width using different approximations for the local-field correction. It is shown that at low density many-body effects due to exchange and correlation considerably modify the thermopower. We find that, for system parameters considered in this paper, the diffusion thermopower is mainly determined by the remote impurity scattering. In the case of the interface-roughness scattering and L > Lc, the diffusion thermopower as a function of carrier density may change sign at low densities due to strong correlation effects. We also discuss the limitations of Mott formula and the deviation from linear temperature dependence of thermopower.