History of the “Detector Materials Engineering” Crystal Growth Process for Bulk Hg1−x Cd x Te

Abstract

This paper reviews the history and technology of a bulk Hg1−xCdxTe crystal growth process that was developed in the early 1980s at Honeywell Electro-Optics Division (presently BAE Systems, Electronic Solutions). The crystal growth process name, DME, was an acronym for the department name: Detector Materials Engineering. This was an accelerated crucible rotation technique (ACRT) vertical traveling heater method growth process. Crystal growth occurred in the pseudobinary Hg1−xCdxTe system. ACRT mixing allowed the lower-density, higher-x-value Hg1−xCdxTe growth nutrient in the upper region of the ampoule to replenish the depleted melt and allowed the growth of constant-x-value, higher-density Hg1−xCdxTe. The material grown by this research and production growth process yielded single crystals that had improved purity, compositional uniformity, precipitate density, and reproducibility in comparison with solid-state recrystallization and other bulk Hg1−xCdxTe growth techniques. Radial and longitudinal nonuniformities in x-value for Hg1−xCdxTe were reduced to <0.0008/cm. The net electrically active background impurities did not exceed 1 × 1014 cm−3. Electron mobilities in excess of 1.5 × 106 cm2/V-s were observed at 77 K. Structural defects of less than 104 cm−2 were measured. Te precipitates were not observed. As a result of these material improvements, long-wavelength infrared (LWIR) photoconductive devices fabricated from DME material had highly desired performance characteristics.