The availability of large volume crystals with the same energy gap in melt-grown CdZnTe (CZT) is restricted due to the Zn segregation in CdTe hosts. We observed the migration of Zn in the solid phase along the positive temperature gradient direction both in situ and post-growth temperature gradient annealing (TGA) of CZT. Diffusivity of Zn obtained from the in situ TGA was approximately 10-5 cm2/s order and completely different mechanism with that of post-growth. The CZT ingots obtained through in situ TGA have uniform Zn and resistivity of 10(10) S2 cm orders. The CZT detectors fabricated from in situ TGA applied ingots exhibit 10% of energy resolution for 59.5 keV peak of Am-241. (C) 2016 Elsevier B.V. All rights reserved.