Galvanomagnetic Effects in a Semiconductor with Two Sets of Spheroidal Energy Surfaces

Abstract

The conductivity, Hall coefficient, and low-field magnetoresistance are calculated for a semiconductor with conduction in two sets of spheroids, one set oriented along [100] directions, the other along [111] directions in reciprocal lattice space. These calculations are used in an analysis of experimental data on alloys of twelve to seventeen percent silicon in germanium. A good fit to the data is obtained assuming such a conduction band, with the shape of the [111] spheroids similar to that found in germanium and the shape of the [100] spheroids like those in silicon. Some interband scattering is introduced to give the observed mobility variation with composition. The calculated energy separations of the [111] and the [100] minima depend strongly on the scattering assumed.