Abstract
Calculations are presented for thermoelectric transport in quantum well and quantum wire superlattices, using (i), the full superlattice electronic band structure in (ii) a multisubband inelastic Boltzmann equation for carrier-phonon scattering. The transport direction is taken to be in the quantum well planes and along quantum wires. It is demonstrated that these two features are needed to give a quantitative treatment of the power factor P in superlattice systems. Results are given for PbTe and for GaAs quantum well and quantum wire superlattices, including the dependence of P on growth direction and on potential offset. For both quantum well and quantum wire superlattices, the dependence of P on potential offset ${V}_{0}$ is found to be qualitatively weaker than in previous work based on the constant relaxation time approximation for carrier scattering. These weaker dependences on ${V}_{0}$ are traced mainly to the enhancement of the electron-phonon scattering rates upon confinement. These results give a different picture of the effects of confinement on P suggesting, for example, that increased confinement in superlattices does not lead to significantly higher P and that free-standing structures, such as free-standing quantum wires, may be particularly attractive for thermoelectric applications.
Published Version
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