Thermal and electrical properties of Czochralski grown germanium-silicon alloys

The thermoelectric parameters, including the thermal conductivity, electrical conductivity and Seebeck coefficient, of high quality crystals of Ge_1-xSi_x alloys in various composition 0<x<1 were investigated at temperatures up to 700 °C. Single and poly-crystals of the alloys of both non-doped and highly Ga-doped were grown by the Czochralski method. The thermal resistivity showed a maximum at x = 0.5-0.6 due to the phonon scattering. The electrical conductivity of non-doped crystals of single and polycrystalline decreased with increasing x, relating to the intrinsic carrier concentration given by the band gap energy at high temperatures. The large magnitude of the Seebeck coefficient was obtained in the GeSi of both single and poly-crystals with x = 0.8-0.9 at elevated temperatures by suitable doping level. The figure of merit of 0.05-0.5 was evaluated in the alloys.