Comparison of thermoelectric properties of p-type nanostructured bulk Si0.8Ge0.2 alloy with Si0.8Ge0.2 composites embedded with CrSi2 nano-inclusisons
Abstract
P-type nanostructured bulk Si0.8Ge0.2 and Si0.8Ge0.2 composites with CrSi2 nano-crystallite inclusions were synthesized via sintering approach. The composite structure showed power factor enhancement compared with nanostructured Si0.8Ge0.2 alloy. The experimental data for both structures were modeled with solving the multiband Boltzmann transport equation in the relaxation time approximation for charge carriers and phonons. The Si0.8Ge0.2 crystallite boundary scattering was modeled by a cylindrical potential barrier at the interfaces and the effects of CrSi2 nano-inclusions were modeled by spherical potential barriers in the Si0.8Ge0.2 lattice. The model calculations revealed that the enhancement in power factor is not an effect of hot carrier energy filtering, but it is due to the enhancement in charge carrier mobility in the composite structure. The analysis of charge carrier mobility components showed that while in nanostructured Si0.8Ge0.2 the ionize impurities and acoustic phonons are dominant scatterers, in the composite structure the scattering by CrSi2 nano-inclusions and acoustic phonons are dominant. The optimum size of the CrSi2 nano-inclusions for enhancing ZT was predicted with the characteristic that ZT drops rapidly when the crystallite size decreases, but it changes slowly as it is increased above its optimum value.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 01, 2012
- Source ID
- 10.1063/1.4764919
Entities
People
- Daryoosh Vashaee
- Zahra Zamanipour
Organizations
- Air Force Office of Scientific Research
- National Science Foundation
- Oklahoma State University–Stillwater