Large-strain dependence of the acceptor binding energy in germanium

Abstract

The strain dependence of the activation energy in p-Ge subject to large (∼0.5%) uniaxial compressional strains has been studied for two different Group III acceptors. For both [100] and [111] compression the energy surfaces have been found to be oblate, that is, m>mII. From Price's theory of the binding-energy strain dependence, the applicable deformation potential elements are found to be b=-2.1 eV and d=-7.0 eV. Unexpectedly orientation-dependent "chemical shift" effects have been found for both Al and In impurities; the deviation of the binding energy extrapolated to infinite strain from that calculated in the effective-mass approximation is found to be ∼4 times as great for [111] strain as for [100] strain. The experimental technique is briefly described. © 1962 The American Physical Society.