Nernst and Ettingshausen Effects in Germanium between 300 and 750°K

Abstract

The Nernst and Ettingshausen effects in germanium single crystals of different conductivity type and with various impurity densities have been measured between 300 and 750\ifmmode^\circ\else\textdegree\fi{}K in magnetic fields of 9000 gauss; the Nernst effect also at 2100 gauss. The experimental results are compared with theoretical expressions for the Nernst and Ettingshausen coefficients and with previously reported values for the thermal conductivity, which links the two effects through the Bridgman relationship. The qualitative agreement is very good, quantitative discrepancies are explained in terms of deviations of the sample mobilities from the theoretically assumed pure low-field lattice mobilities and by uncertainties in the numerical values used for the theoretical calculations. A derivation of the Nernst constant in the range of negligible phonon-drag effect is given, based on the analogy between thermo- and photomagnetoelectric effects.