Thermal and electrical properties of Czochralski grown GeSi single crystals

Single crystals of Ge_1-xSi_x alloys in the composition range 0 < x < 1 non-doped and doped with boron, gallium, and phosphorus as an impurity were grown by the Czochralski method. The measurements of the thermal conductivity (κ), electrical conductivity (σ), and Seebeck coefficient (α) of the grown crystals were performed in the temperature range 300-1000 K. The thermal conductivity κ shows a minimum (κ ∼ 3.5 W/K·m) around the Si content x = 0.5 - 0.7, which can be explained by the phonon scattering due to a distortion of the crystal lattice. The Seebeck coefficient α was 300 - 400 μV/K at 600°C in the impurity-doped GeSi alloys. An |α| vs 1n (σ) plot of highly impurity-doped GeSi alloys obeys a linear relation. The slope of the straight line is 1.2 k/e, indicating the corporation of the charged impurity into the alloy scattering mechanism.