Enhanced thermoelectric performance in PbTe-based superlattice structures from reduction of lattice thermal conductivity

• Published in: Applied physics letters 2005-07, Vol.87 (2), p.023105-023105-3
• Main Authors: Caylor, J. C., Coonley, K., Stuart, J., Colpitts, T., Venkatasubramanian, R.
• Format: Article
• Language: English
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.1992662

We have fabricated two-dimensional n -type Pb Te ∕ Pb Te 0.75 Se 0.25 structures using an evaporation process. In optimized films exhibiting a high-quality superlattice structure, a significant reduction in lattice thermal conductivity has been experimentally measured. The reduction would indicate enhanced thermoelectric device performance compared to standard PbTeSe alloys given that the electrical components, specifically, the Seebeck coefficient and electrical resistivity, were not observed to deteriorate from bulk values. The analysis of these films shows continuous layers with a true two-dimensional superlattice structure, as opposed to the Pb Te ∕ Pb Se system that exhibits zero-dimensional structures from self-assembly. The room-temperature measurement of cross-plane figure-of-merit in a n -type Pb Te ∕ Pb Te 0.75 Se 0.25 device structure by the transient method has been combined with temperature-dependent measurements of in-plane resistivity and Seebeck coefficient to yield evidence of enhanced thermoelectric performance. The similarities and differences between the superlattice in the Pb Te ∕ Pb Te 0.75 Se 0.25 system and the Bi 2 Te 3 ∕ Sb 2 Te 3 material system are presented.