Anisotropy of the mobility in a-edge-dislocated tellurium crystals

Abstract

Dislocations of the a-edge type were generated by homogeneous deformation in pure Te crystals. Two different directions of strain were used to stimulate either one glide system only (single-a glide) or two glide systems simultaneously (double-a glide). The arrangement of the dislocation lines in layers parallel to the activated glide planes could be observed by etch pit techniques. The authors measured the specific resistance and the Hall coefficient in the temperature range between 20 and 180K to obtain the hole mobility. This mobility decreases because of scattering processes by the dislocations. Besides this a clear anisotropy of the hole mobility in the basal plane of the crystal is detected depending on the current direction as to the activated glide planes. The results have been compared with a model calculation which is based on the energy-loss method. The calculated expression of the reciprocal mobility can be fitted to the experimental results including the correct anisotropy and the used fit parameters agree with the experimental results.