Thermal conductivities of silicon and germanium in solid and liquid states measured by non-stationary hot wire method with silica coated probe

The thermal conductivities of silicon and germanium have been determined using the non-stationary hot wire method. Measurements were carried out over the temperature range 293–1724 K on solid and liquid silicon and on liquid germanium in alumina tube. For solid silicon, the thermal conductivities were about 139 W/mK at 293 K and 19 W/mK at 1573 K and displayed temperature dependence steeper than T � 1 ; where T is the temperature. Calculation of thermal conductivities for solid silicon based upon isotope, three-phonon and four-phonon scatterings indicates that phonon conduction dominates heat conduction at temperatures below 1000 K. At temperatures above 1000 K, on the contrary, contributions from electron, hole and electron–hole pair to heat conduction became greater progressively with a temperature rise. For liquid silicon, the thermal conductivity was about 57 W/mK at 1700 K and exhibited a slight increase with an increase in temperature. The thermal conductivity of liquid germanium was about 43 W/mK at 1273 K and slightly increased with increasing temperature. In both liquids, temperature dependency of thermal conductivity values was discussed from the view point of the Wiedemann–Franz law. r 2002 Elsevier Science B.V. All rights reserved.