Growth of large diameter (Hg,Cd)Te crystals by incremental quenching

Abstract

The growth of large (20 mm diam by 50 mm length) Hg1−xCdxTe crystals by incremental quenching of large volume Hg1−xCdxTe alloy melts was demonstrated. This method is based on the sequential freezing of shallow melts that have large surface to volume ratios onto a large diameter growing ingot. The resulting homogeneous polycrystalline ingots were annealed at 665 °C to promote grain growth. Grain sizes ranging from 25 to 35 mm were obtained after annealing at 665 °C for 28 days. In addition, the crystals showed very little substructure and had dislocation densities of 1.25±0.6×105 cm−2. Hall effect measurements on wafers annealed at temperatures below 300 °C show an n-type behavior with carrier concentrations ranging from 3.3×1014 to 4.8×1014 cm−3 and majority carrier mobilities ranging from 1.69×105 to 2.29×105 cm2/V s at 77 K for a composition x=0.225. The compositional variation Δx in the radial and axial direction was measured by several techniques and was found to range from 0.005 to 0.01.