Peer-Reviewed Journal Details
Mandatory Fields
Murphy-Armando, F
2019
December
Journal of Applied Physics
Enhancement of the electronic thermoelectric properties of bulk strained silicon-germanium alloys using the scattering relaxation times from first-principles calculations
Validated
Optional Fields
TEMPERATURE-DEPENDENCE DIRECT-GAP MOBILITY RESISTIVITY SI
126
We use first-principles electronic structure methods to calculate the electronic thermoelectric properties (i.e., due to electronic transport only) of single-crystalline bulk n-type silicon-germanium alloys vs Ge composition, temperature, doping concentration, and strain. We find excellent agreement to available experiments for the resistivity, mobility, and Seebeck coefficient. These results are combined with the experimental lattice thermal conductivity to calculate the thermoelectric figure of merit ZT, finding very good agreement with experiments. We predict that 3% tensile hydrostatic strain enhances the n-type ZT by 50% at carrier concentrations of n = 10(20) cm(-3) and a temperature of T = 1200 K. These enhancements occur at different alloy compositions due to different effects: at 50% Ge composition, the enhancements are achieved by a strain induced decrease in the Lorenz number, while the power factor remains unchanged. These characteristics are important for highly doped and high temperature materials, in which up to 50% of the heat is carried by electrons. At 70% Ge, the increase in ZT is due to a large increase in the electrical conductivity produced by populating the high mobility Gamma conduction band valley, lowered in energy by strain. Published under license by AIP Publishing.
MELVILLE
0021-8979
10.1063/1.5117345
Grant Details