Status of the improved N-type SiGe/GaP thermoelectric material

A comprehensive experimental and theoretical work has been conducted in order to optimize the thermoelectric properties of n‐type SiGe materials. A key factor to the improvement of the figure of merit Z of these materials has been the successful ability to substantially increase the electron concentrations by up to a factor of two at room temperature over current standard P‐doped n‐type SiGe materials using a Ga and P as dopants. Particular emphasis has been placed upon the understanding of the changes in P solid solubilities when multi‐doping with both Ga and P, and upon the relationships between electrical and thermal properties with microstructure and composition of heavily doped hot‐pressed SiGe materials. Application of the results obtained from a set of various experimental techniques coupled with thermodynamic theoretical considerations resulted in reproducible improvements for several SiGe/GaP samples with average Z values close to 1×10−3 K−1 over a 600–1000°C temperature range.