Comparative study of dislocation densities in CdZnTe ingots grown with different carbon coatings

Cadmium Zinc Telluride (CdZnTe) is known to be one of the best room temperature X-ray and gamma-ray radiation detector´s materials. However, the supply of high-quality CdZnTe detectors is limited due to crystal defects such as dislocations, impurities, Te inclusions that are generated during the crystal growth process. Dislocations are generated due to the stress/strain in the growth process. In this study, we characterized dislocation densities in CdZnTe crystals grown by different techniques (i.e. different carbon-coating thickness and ampoule´s shapes) for the suggestion of better growth techniques. Dislocations densities were revealed using a Saucedo solution and analyzed by an infrared microscope. The thick carbon-coated ampoules generated fewer dislocations than the thin carbon-coated ampoule and the ampoule design did not affect the etch pit densities (EPD) as much than carbon-coating thickness. Also, we concluded that a proper crystal growth rate and cooling down rate is one important factor in minimizing dislocations in CdZnTe crystals. The effects of dislocations on the CdZnTe detector´s performance was evaluated from the ²⁴¹Am gamma-response, which fabricated from low and high densities of etch pit region.