Non-stoichiometry and problem of heavy doping in semiconductor phases

The experimental results on the influence of non-stoichiometry on defect structure, band structure and physical properties of the IV-VI and I-III-VI2 semiconductor compounds with wide homogeneity regions were analyzed. It was shown that compositions at which peculiarities in the concentration dependences of properties in the homogeneity region are observed, correspond to the maximum in the melting curves. Using the approach of percolation theory, the transition from weak to heavy self-doping within the homogeneity region was considered, and the percolation threshold under the introduction of non-stoichiometric defects was estimated. Compositions optimal for long-range ordering were deter-mined. (C) 2003 Elsevier Ltd. All rights reserved.