Strain Dependence of the Minority Carrier Mobility inp-type Germanium

The strain dependence of the minority carrier drift mobility in uniaxially compressed bars of $p$-type germanium has been determined at constant temperatures between 77 and 300°K. The minority carrier mobility was measured by performing a series of Haynes-Shockley drift-mobility experiments in which both the applied stress and the electron drift path were along a $〈111〉$ crystal direction. The observed variation in electron mobility versus strain is compared with theoretical estimates based on a strain-induced population transfer in the conduction band. This comparison yields a value for the shear deformation-potential constant ${\Xi }_u=16.3\mathrm{}\pm 0.3$ eV. The scattering anisotropy ${\kappa }_{\tau }$ has also been determined from the saturated mobility values. The presence of Coulomb-type scattering, as manifested by an increase in ${\kappa }_{\tau }$, is noticeable at lower temperatures. However, values for ${\kappa }_{\tau }$ found for minority electrons in $p$-type material are not significantly different from those obtained from saturated piezoresistance measurements using $n$-type samples having the same net impurity content.