Electronic Effect in the Third-Order Elastic ConstantC456ofn-Germanium

Abstract

The doping of germanium with ∼3×${10}^{19}$/${\mathrm{cm}}^3$ arsenic atoms has been observed to change the magnitude and reverse the sign of the third-order elastic constant $C_{456}$. Room-temperature measurements of the change of $C_{456}$ and of the change of the shear modulus $C_{44}$ upon doping are reported for two degenerate samples relative to a pure sample. By attributing these impurity effects to the electronic mechanism proposed by Keyes, the shear deformation potential constant ${\Xi }_u$ is found to be 17.0±0.2 eV, and the carrier densities of the degenerate samples are determined, in excellent agreement with the results of transport measurements.