Interplay mechanism between secondary phase particles and extended dislocations in CdZnTe crystals

Abstract

To interpret the interplay mechanism of dislocations associated with secondary phase (SP) particles, <111> CdZnTe crystals are annealed at isothermal and thermal gradient conditions under Cd/Zn and Te overpressure, respectively. The etching pit arrangement surrounding Te-SP is evaluated to gain an insight into the generation and multiplication of induced dislocations. It is demonstrated that Te-SP dissociation dominates the volume variation during isothermal annealing. This dissociation is enhanced under Cd/Zn overpressure due to an exothermic reaction, which results in the activation of dislocation glide and climb systems and, simultaneously, the diffusion of Te_i. In turn, ‘radial-shaped’ dislocation rosettes and ‘star-shaped’ dislocation clusters appear on the {111}_B surface after preferential etching. However, for thermal gradient annealing, Te-SP thermomigration predominates. The induced dislocation density is related to the Te droplet drift velocity. Meanwhile, Cd/Zn and Te overpressure could promote or slow down the migration. Interestingly, no remarkable dislocation rosettes or clusters are observed after temperature gradient annealing under Te overpressure.