Phonon conductivity of Ge in the temperature range 2-1000 °K

Abstract

The contributions of transverse and longitudinal phonons toward thermal conductivity of undoped Ge have been investigated, both in high- as well as low-temperature regions. Four-phonon processes are also included in the determination of the combined relaxation time τc and hence the phonon conductivity. The group velocity of respective phonons in the conductivity integral is obtained on the basis of q→=(ωv→)(1+αω2) , where the parameter α is determined from the experimentally obtained dispersion curves for the different acoustic branches in the region 0-12qmax and 12qmax-qmax. It is observed that the transverse phonons in general make a major contribution toward thermal conductivity in the entire temperature range. © 1971 The American Physical Society.