Electrical Properties of Lead Telluride

Abstract

Samples of n‐type PbTe crystals with different electron concentrations (n=2×10¹⁷∼5×10¹⁹/cc) were prepared by impurity doping or by heating in the vapor of lead. The electrical properties of these crystals were independent of the kind of impurities and depended only on the electron concentration. The electron mobilities of our samples were proportional to n^−⅓ at 77°K, and to n^−4/3 at 4.2°K. As the conduction electrons in our samples are degenerate at these temperatures, the experimental results mentioned above suggests that the conduction electrons in PbTe crystals are scattered mainly by acoustical mode at 77°K and by neutral imperfections at 4.2°K. Since the electron mobility in PbTe becomes very large at 4.2°K (e.g., 1∼4×10⁶ cm²/v‐sec), this material is quite suitable for the experimental studies of the quantum transport phenomena. To investigate such phenomena, the Hall and magnetoresistive effects of n‐type PbTe crystals were measured at 4.2°K in a pulsed magnetic field up to 170 kgauss. In the specimens with relatively low electron concentrations (e.g., n≃3×10¹⁷/cc), the magnetoresistive effect had a single minimum at about 77 kgauss in a transverse magnetic field, and at about 55 kgauss in a longitudinal field. This minimum should correspond to the situation where the Landau level with l = 1 coincides with the Fermi level in the PbTe crystals.