The incorporation mechanisms of native defects and dopants in bulk and epitaxially grown material were reviewed, and the origin of native defect-related deep centers was examined with regard to their reduction. The situation was found to be complicated by the possible occurrence of other sorts of native defect. One type was an anti-structure donor defect such as TeHgm, where m was an integer which represented the degree of ionization of the defect. In principle, m could take values which ranged from 1 to 4. It could be shown that the concentration of these anti-structure defects varied as PHg-2, regardless of their charge state, provided that the intrinsic carriers dominated the electro-neutrality condition of the crystals. Hence, as the Hg partial pressure was decreased in order to decrease the concentration of Hg interstitials, the concentration of the Te anti-structure donor defects increased. Although their concentrations were not sufficiently high to be a major species in the charge balance of the crystal, their concentration at low Hg pressures could be of the order of 1013/cm3. It was concluded that, if Te anti-structure defects were also potential Shockley-Read centers, the optimum preparation condition was one in which the crystal was treated at an intermediate Hg pressure; such that the concentrations of both Hg interstitial donors and Te anti-structure donors were minimal. Regardless of whether the material was p-type or n-type, a reduction in the numbers of these native defect-related Shockley-Read centers was expected to lead to improvement.

H.R.Vydyanath: Journal of Crystal Growth, 1996, 161, 64-72