Origin of negative magnetoresistance in heavily dopedn-type silicon and germanium

Abstract

A model for the magnetoresistance in the metallic phase of heavily doped $n$-type Si and Ge is presented. The experimentally observed anomalous behavior is reproduced within the right order of magnitude without the introduction of adjustable parameters. The origin of the anomalous negative magnetoresistance is in our treatment found to be the variation, with the applied magnetic field, of the effective mass of spin-up and spin-down electrons at the Fermi surfaces. The modification of the density of states due to electron and electron-donor-ion interactions is studied and found to be of utmost importance.