Thermoelectric Power and Resistivity of Solid and Liquid Germanium in the Vicinity of Its Melting Point

Abstract

The thermoelectric power of germanium against platinum has been measured between room temperature and 1030°C (melting point is 937°C). Five specimens were studied in the solid phase (three polycrystalline and two single crystalline specimens), and two in the liquid phase (one n type and one p type at room temperature). It is found that the absolute thermoelectric power Q of high purity (50–70 ohm-cm) germanium is nearly linear in 1/T only for the range 0.83<(1000/T)<1.5, or 400<T<937°C. The value of Q for our crystals at temperatures below 400°C is less negative than would be required by an extrapolation of the straight line Q=+140−280(1000/T) μv/deg which represents fairly well the high temperature data. This discrepancy may be due to the presence of very small amounts of acceptor impurity (perhaps boron) in our crystals. The thermoelectric power between liquid and solid germanium is approximately 70 μv/deg, and the liquid is positive relative to the solid. The absolute thermoelectric power of the liquid is very nearly zero and is nearly independent of temperature. Finally, the resistivity of germanium decreases by a factor of approximately 19 upon melting, and is approximately 63 microhm-cm in the liquid phase.