Crystal growth of Cd_1−xZn_xTe and its use as a superior substrate for LPE growth of Hg_0.8Cd_0.2Te

Cd_1−xZn_xTe (x=0.04) boules providing wafers with single crystal areas as large as 10 to 12 cm² have been grown by the vertical modified‐Bridgman (VMB) technique and evaluated as an alternative to CdTe for use as substrates for LPE growth of HgCdTe layers. The CdZnTe crystals, as compared with typical CdTe crystals, exhibit lower defect densities, increased mechanical strength, and significantly improved macro‐ and micromorphologies of LPE layers of HgCdTe grown on them. The surface morphology of LPE layers grown on CdZnTe substrates shows less orientation dependence than for layers grown on CdTe substrates, for orientations close to the {111} planes. The addition of Zn to the CdTe lattice may result in increased covalency and reduced ionicity, which in turn inhibit plastic deformation and generation of dislocations. These factors, combined with the ability to adjust the lattice constant to any desired value within the two extrema, allow the growth of low‐defect density HgCdTe layers required for high‐performance IR detector arrays. The quality of the substrates and epitaxial layers has been evaluated by defect etching, infrared microscopy, x‐ray rocking curve analysis, and x‐ray topography.