Modeling-based optimization of thermoelectric nanostructures

O.L. Lazarenkova1,* ,A.A. Balandin1

1Nano-Device Laboratory, Department of Electrical Engineering, University of California - Riverside, Riverside, California 92521 USA

Quantum dot superlattices (QDS) and quantum wire arrays (QWA) have been recently proposed for thermoelectric applications. Strong improvement of the thermoelectric properties in such structures is expected only if the structure parameters are carefully tuned to achieve desired carrier and phonon transport characteristics. The latter motivates this theoretical study of carrier and phonon spectra in such nanostructures. In this paper we present our approaches for calculating thermoelectric characteristics in three-dimensional regimented QDS and QWA. Based on our model, we carry out structure optimization for p-type QDS of InAs/GaAs, Ge/Si, and PbSe0.98Te0.02/PbTe. We show that when conditions for mini-band formation are satisfied, carrier transport in such structures can be tuned in a favorable way leading to large carrier mobility, Seebeck coefficient, and the thermoelectric figure-of-merit. To maximize the improvement one has to tune the parameters of QDS in such a way that electrical current is mostly through the well-separated below-the-barrier mini-bands of relatively large width of several kBT [1].

[1]. A.A. Balandin and O.L. Lazarenkova, Appl. Phys. Lett., 82, 415 (2003).

The work was supported in part by NSF NER projects ECS-0210282 on QDS.

*Present address: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 USA