Characterization of in-situ doped poly-SiGe thermoelectric materials

Abstract

This paper presents characterizations of p-typed and n-typed polycrystalline silicon germanium (poly-SiGe) as key materials of thermoelectric generator for energy-scavenging application. Four key material properties - Seebeck coefficient, electrical resistivity, thermal conductivity and specific contact resistance- were measured to determine the figure-of-merit (ZT) as a performance measurement of the materials. Measured Seebeck coefficients are 34 µV/K for p-type and 185 µV/K for n-type. Thermal conductivity is around 3 W/mK. Contact resistance is still considerably high and there is no significant reduce on the value as annealing temperature increased from 375°C to 475°C for annealing time of 30 and 60 minutes. The value of ZTs for p-type and n-type material are 0,0086 and 0,063 respectively. From ZT value alone, it can be seen that ZT of p-SiGe should be improved. Since the value of total electrical resistance is determined by the material itself, further work on Ge and doping level variations is required as well as optimization of annealing temperature and time to reduce contact resistance.