A quasi-chemical formalism was used to make quantitative predictions concerning the native point defect densities in Hg0.8Cd0.2Te. The electronic contribution to the defect formation free energy was calculated by using the self-consistent first-principles full-potential linearized muffin-tin orbital method, and the local density approximation. A gradient correction was added to the latter results so that absolute account could be taken of the chemical potential of the Hg vapor phase. A Green's function approach, based upon a valence force field plus a point Coulomb model, was used to calculate the vibrational contributions to the defect free energy. It was found that the double acceptor Hg vacancy was the predominant defect; in agreement with previous interpretations of experiments. The Te antisite was also found to be an important defect. Predictions of the low-temperature hole concentrations were made as a function of annealing temperature, and were compared with available experimental data. The order of magnitude of the predictions agreed well with experimental results, and discrepancies were attributed to contributions to the free energy which had been neglected, or to inaccuracies in the intrinsic reaction constant that had been used.

M.A.Berding, M.Van Schilfgaarde, A.Sher: Physical Review B, 1994, 50[3], 1519-34