Effect of Te atmosphere annealing on the properties of CdZnTe single crystals

Low-resistivity CdZnTe:In (CZT:In) single crystals were annealed under Te atmosphere according to the behaviors of deep-donor Te antisite. The results indicated that the star-like Cd inclusions were completely eliminated after 120 h annealing. Meanwhile, the resistivity is greatly enhanced. The resistivity of the slice annealed after 240 h was achieved as high as 1.8×1011 Ω cm, five orders of magnitude higher than that of as-grown slice. It suggested that the deep-donor level Te antisites were successfully introduced to pin the Fermi level at the mid band-gap position. The IR transmittances of the slices were also improved, which increased as the annealing time increased. PL measurement revealed that the (D0,X) peak representing high quality of CZT crystal appeared. It can be concluded that the quality of CZT crystals is obviously improved after annealing under Te atmosphere.

► High resistivity is due to deep-donor level TeCd.
► The resistivity achieved was as high as 1.8×1011 Ω cm.
► Star-like inclusions are Cd inclusions.
► (D0,X) peak represents the improvement of the crystal quality.