Low Temperature Transport Properties Of Arsenic Single Crystals (semi-metals).

Abstract

Measurements of the thermal conductivity, thermoelectric power, and electrical resistivity of arsenic single crystals have been performed from room temperature to as low as 15 mK. The purpose of these investigations was to establish, in some detail, the nature of the transport properties of this largely neglected semimetal, and to compare the results with the two more familiar members of the Group V semimetal trio, bismuth and antimony. The thermal conductivity of arsenic has been measured in the temperature range 2K-300K in two distinct crystallographic directions, and the lattice and carrier contributions have been separated by use of a strong transverse magnetic field. Analysis of the results shows a strong degree of interplay between phonons and carriers, with a significant dependence on sample quality. Scattering mechanisms limiting the carrier and phonon heat flows are discussed in detail. Measurements of the thermoelectric power reveal quite spectacular behavior, indicative of contributions from both carrier diffusion and phonon drag. A simple model addressing the magnitudes of these two distinct contributions to the thermopower is presented and analyzed. Finally, high precision investigations of the electrical conductivity at very low temperatures indicate that the resistivity decays as T('n) with n greater than 3 below 2K. The results are analyzed in terms of carrier-phonon scattering on both spherical and cylindrical Fermi surfaces.