Progress in the optimization of n-type and p-type SiGe thermoelectric materials

A comprehensive experimental and theoretical work has been conducted in order to optimize the thermoelectric properties of Si80Ge20 materials and reach the goal of a combined figure of merit value of 0.85×10−3 K−1 averaged over 600–1000 C temperature range. Improvement for the n‐type material have been obtained by determining the optimum amounts of gallium and phosphorus dopants necessary to achieve optimum carrier mobility and concentration. The emphasis is now on the good reproducibility of these results through understanding and control of the processing parameters relating microstructure and composition to the transport properties. The optimum doping level has now been firmly established for p‐type materials, and work is concentrating on the reduction in thermal conductivity. BN ultra fine particles have been successfully incorporated into fully dense samples and have resulted in desired improvement of the figure of merit. Efforts are being made to reproduce these encouraging results.