Growth of In doped CdZnTe by vertical Bridgman method and the effect of In on the crystal properties

An Indium (In) doped Cd_0.9Zn_0.1Te (CdZnTe:In) ingot was grown by vertical Bridgman method. The distribution of In in the ingot was analyzed. It was evaluated that the segregation coefficient of In in CdZnTe during the growth was 1.3, which caused a higher In concentration in the initial part of CdZnTe:In ingot and a lower In concentration in the final part. In was also enriched at the grain boundaries but homogeneously distributed inside the grains in the as-grown crystal. Photoluminescence spectra indicated that In had two states existing in the CdZnTe:In ingot. One was interstitial neutral In and the other was substitutional ion In⁺. The two states led to the two donor levels at 0.12 and 0.04eV in CdZnTe:In band construction, respectively. IR transmission measurements exhibited that CdZnTe:In was almost opaque to IR emission when the wavenumber was larger than 1000cm^-1, then was 24% transparent when the wavenumber was decreased to lower than 1000cm^-1. This phenomenon also confirmed the existence of the donor level of 0.12eV demonstrated by the PL spectra. Resistivity measurements revealed that CdZnTe:In obtained three orders higher resistivity than CdZnTe. It meant that doping of In into CdZnTe could improve the crystal properties.