Morphology evolution of micron-scale secondary phases in CdZnTe crystals grown by vertical Bridgman method

The morphology and evolution of micron-scale Te-rich secondary phases (SP) are discussed based on IR contrast images. Well-defined, hexagonal or triangular shaped, incoherent Te-rich SP particles were generally identified in as-grown CdZnTe crystals grown with excess Te. The creation of these particles is consistent with the Te-rich droplets encapsulated within the CdZnTe matrix, which grown by accumulation of the point defects. The surrounding CdZnTe crystal dominates the morphology of Te-rich SP particles orienting themselves along crystallographic directions. Star-shaped Te-rich particles and needle-like Te-rich SP clusters were normally revealed in as-grown CdZnTe crystals, obtained under Cd-rich conditions. The former is related to the dislocation loop punching associated with SP particles, which attributed to the internal stress relief. The latter is constituted by numerous small irregular Te precipitates, which is likely produced by the aggregation of Te precipitates along specific paths through thermo-migration during the in situ annealing and cooling processes.