Intrinsic thermoelectric figure of merit of bulk compositional SiGe alloys: A first-principles study

A systematic study based on state-of-the-art first-principles calculations has been carried out to determine intrinsic thermoelectric properties in n- and p-type SiGe alloys. Both electronic and thermal transport coefficients have been evaluated using the Boltzmann transport equation, applied on the electronic and phonon band structure, respectively. The Seebeck coefficient, electrical conductivity, and thermal conductivity have been analyzed focusing on the effect of carrier concentration, temperature, and alloy composition. The resulting figure of merit is highest for heavy doping and at elevated temperatures (>1000 K) in the SiGe alloy with Ge content from 50% to 80%.