Effect of CZT Powder Burying CZT Crystal on Annealing in Cd Atmosphere

Due to the inevitable formation of the second phase of Te in the growth process of Cadmium zinc telluride (CdZnTe/CZT) crystal, the Te related defects are usually treated by Cd atmosphere annealing to improve the crystal quality. In this paper, the influence of different powder burying crystals on the annealing effect in Cd atmosphere is studied by analyzing the change of crystal surface components, removal effect of Te inclusion, electric field distribution and carrier transport characteristics. The results show that burying the crystal with powder helps to maintain the crystal surface composition in annealing, but the Te inclusion can be eliminated only by controlling the amount of powder. Moreover, it is found that the uniformly distributed Te inclusions tend to migrate to the surface during the annealing process, while the Te inclusions at dislocation or crystal boundary are difficult to eliminate. It is speculated that the internal Te loading is more inclined to the reaction of diffused Cd atom, which makes the Te inclusions decrease continuously. After annealing with proper amount of powder, due to the elimination of Te inclusion defects, the electric field distribution inside the crystal is more uniform and the carrier lifetime product is improved.