Thermoelectric properties of N-type Si80Ge20 doped with P

Dopant P was used to increase the carrier concentration and ultra high pressure sintering method was used to change the structure of N-type Si80Ge20 to obtain high thermoelectric figure of merit. With pure Si, Ge, P powder as raw materials, N-type Si80Ge20 was synthesized in vacuum atmosphere. After being crushed and cold compacted, they were sintered by ultra high pressure sintering method. Their phase composition, crystal structure and morphology were characterized by XRD and SEM. During temperature range form 300K to 900K the electrical conductivity was measured by direct current method, the Seebeck coefficient was measured with the temperature difference applied along to the sample's two ends. The dependences of thermoelectric properties of samples on the composition and the temperature were studied. The results indicate that the samples was not well densified by ultra high pressure sintering method, the compactness was about 80%, which induce low electrical conductivity, appropriate amount of P dopant was conducive to improve the thermoelectric properties of Si80Ge20, and the ZTmax value of 0.89 was obtained for the sample doped with 0.06at% P at 822K.