Study of the local defect structure of CdTe-Ge crystals by microindentation

This paper demonstrates the effectiveness of the microindentation method as a way to monitor the quality of cadmium telluride crystals. Measurements of microhardness and the length of dislocation rays from the rosette around the indentation pit can clearly identify nonuniform distributions of structural defects, both along the direction of growth and along a diameter of a CdTe boule. The mobility of α dislocations is more sensitive to nonuniformities in the structure than the mobility of β dislocations and the microhardness. A qualitative correspondence is established between the microplasticity characteristics of CdTe:Ge and its germanium content: the hardness of the crystal is insensitive to changes in the Ge content in the range from 3×1016 to 1×1017 at/cm3, but increases sharply beginning at a concentration of ∼1×1017 at/cm3. The correlation between the value of the microhardness and the length of the dislocation rays from the rosette around the imprint of the indentor are analyzed. An estimate is obtained for the hardness of pure CdTe.