Accession Number : AD0274541

Title :   THE EFFECTIVE MASSES OF FREE CARRIERS IN PBTE: THEIR TEMPERATURE DEPENDENCE AND CONTRIBUTION TO TRANSPORT PROPERTIES

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE ENERGY CONVERSION AND SEMICONDUCTOR LAB

Personal Author(s) : LYDEN,HENRY A.

Report Date : 15 JAN 1962

Pagination or Media Count : 1

Abstract : The temperature dependence of the mobility of the semiconducting compound PbTe has posed something of a problem in that it apparently does not conform to the theoretical behavior. The origins of this behavior are presented in this investigation. A procedure was developed to determine the conductivity effective mass from the wavelength of the infra-red reflectivity minimum resulting from the free-carrier dispersion. The conductivity effective mass was determined as a function of temperature for (5) samples of lead telluride. A very pronounced temperature dependence was observed. In addition, the thermoelectric power has been measured between 77 and 300 K for these five samples. From these data, the reduced Fermi potential energy and the density-of-states effective mass were determined over this same temperature range. An acoustical mode mobility also has been synthesized from these data. From the amount of optical mode scattering required to fit the observed mobility behavior, it has been deduced that PbTe should not be classified as a predominately polar compound since it has a very low degree of ionicity. Finally, the thermal conductivity of these same samples of PbTe has been measured between 100 and 300 K. (Author)

Descriptors :   *SEMICONDUCTORS, *TELLURIUM COMPOUNDS, *THERMAL CONDUCTIVITY, *TRANSPORT PROPERTIES, CRYSTAL LATTICES, LEAD(METAL), MAGNETIC FIELDS, MEASUREMENT, RELAXATION TIME, SCATTERING, TEMPERATURE, THERMOELECTRICITY

Distribution Statement : APPROVED FOR PUBLIC RELEASE