LOW-TEMPERATURE THERMOELECTRIC POWER OF HEAVILY DOPED n-TYPE GERMANIUM

Abstract

A large, temperature-dependent component in the low-temperature thermoelectric power of heavily doped n-type germanium has been observed in the temperature region of liquid helium. All of the samples (6.8–62 × 1017 per cm3) exhibit a negative magnetoresistance in the low-temperature region which saturates at reasonably low magnetic-field values. On the basis of an assumed magnetic scattering, the magnetoresistance and magnetic susceptibility data have been analyzed in order to estimate the magnitude and concentration of the localized magnetic moment of the spin-scattering center, and also to estimate the exchange integral giving rise to the coupling between the mobile carriers and the localized impurity electrons. The resistivity behavior, in both a finite and zero magnetic field, appears to be best described by assuming an antiferromagnetic transition in the region of the thermoelectric anomaly. Attempts are made to interpret the observed temperature dependence of the thermopower. However, as yet, there is no quantitative theory to predict the thermoelectric behavior of a degenerate semiconductor in the presence of antiferromagnetic ordering.