Effects of Zn addition and thermal annealing on yield phenomena of CdTe and Cd0.96Zn0.04Te single crystals by nanoindentation

Mechanical yield phenomena in CdTe and CdZnTe single crystals for use as radiation detectors were studied by nanoindentation, since dislocations can act as electrically active levels that would impact device performance. The initial deformation behavior prior to yielding is elastic for as-grown crystals, indicating that rapid dislocation nucleation is the controlling mechanism for the observed yield point. Zn doping increases the stress required for initiating plastic deformation from 0.76 GPa in CdTe to 1.29 GPa in CdZnTe, and increases the flow stress of the material from solid solution hardening. Thermal annealing leads to plastic loading at very low loads, suggesting that annealing CdZnTe generates a low but increased density of dislocations in the bulk material.