Thermoelectric figure of merit enhancement in a quantum dot superlattice

We theoretically investigated electron and phonon transport in a quantum superlattice and evaluated a possible thermoelectric figure of merit increase. The presented model takes into account electron and phonon transport modifications due to the space confinement caused by the mismatch in electronic and thermal properties between dot and host materials. The numerical calculations were carried out for a structure that consists of multiple layers of Si with regimented quantum dots separated by wetting layers and spacers. Transport coefficients (electric conductivity, Seebeck coefficient and lattice thermal conductivity) were calculated as functions of quantum dot volume fraction for different dot sizes. It is shown that additional thermoelectric figure of merit enhancement due to the presence of quantum dots may be obtained. The predicted enhancement is mostly due to the significant drop in the lattice thermal conductivity caused by the acoustic phonon scattering by quantum dots.