Features of tensoresistance depending on the crystallographic orientation of γ-irradiated (60Co) germanium and silicon single crystals

The features of the longitudinal tensoresistance of γ-irradiated (60Co) n-Ge and n-Si crystals, as well as γ-irradiated n-Ge crystals after n→p conversion, at fixed temperatures depending on the direction (X→∥J→∥ [111,110], [100]) of application of the mechanical compressive stress 0≤X≤1.2GPa were investigated. The charge carrier concentrations and the Hall mobility values before and after γ-irradiation were controlled by measurements of the Hall effect. It was established that under conditions of the nonsymmetrical arrangement of deformation axis relative to the isoenergetic ellipsoids, the dependences of tensoresistance in the γ-irradiated n-Ge and n-Si crystals pass through a maximum. With a symmetrical placement of the deformation axis such maximum is not observed. In the converted n-Ge crystals under applying of mechanical stress the presence of the region of the increasing resistivity in the initial area of deformation was found, which is explained by increase of the energy gap between the deep level and the top of the valence band with increasing pressure.