Anion substitution in zinc chalcogenides

Abstract

Anion substitution effects on the structure and energy of zinc chalcogenides were studied with the semiempirical molecular orbital method MSINDO. Cyclic clusters of different sizes were chosen as model systems. The convergence of the bulk properties of the perfect clusters with increasing cluster size was tested. Single and multiple substitution of oxygen atoms in zinc oxide by sulfur and of sulfur atoms in zinc sulfide by oxygen served to determine the energetics of substitution for these two cases. It was found that the substitution of oxygen by sulfur in ZnO is easier than the substitution of sulfur by oxygen in ZnS in agreement with experimental results. The interaction between two oxygen atoms vs. two selenium atoms in zinc sulfide was investigated. Oscillations of the cluster energy in dependence of the distance between the two doping atoms were observed. These are explained by the relative sites of the doping atoms in the crystal lattice. The magnitude of the oscillations is smaller in ZnS:Se than in ZnS:O, because the difference between the anion radii of S2- and Se2- is smaller than between S2- and O2-. This is also reflected in the band gap.

International development of chemical vapor deposited zinc sulfide

“…51 By combining sensitive optical techniques, such as photoluminescence or cathodoluminescence with ab initio atomistic models of ZnS (e.g. 89,90 ) to probe bandgap defect states, the relevant defects can be clearly identified and processing steps can be modified to remove the undesirable ones.…”

Molecular Dynamics Study of the Thermal Entropy in Mixed Zinc Chalcogenides

“…This technique leads to thermodynamically stable states. In our previous work, we studied the miscibility of ZnS/ZnSe and ZnO/ZnS and found continuous mixing in the first case but no mixing in the second case at 1000 K. Mixing was predicted only at higher temperatures in contrast to the experiments. There could be two reasons for this discrepancy: (1) the small size of the cyclic cluster used for the simulation of the solids and (2) the neglect of the vibrational contribution to the entropy of mixing.…”

Influence of intrinsic defects on the properties of zinc oxide

“…For larger distances, the energy increases, but there is also an oscillation as in the case of two doping sulfur atoms. 29 The increase in defect formation energy compared with the most favorable arrangements of Table 1 does not exceed 116 kJ/mol. This means that the maximum defect formation energy E d for a fully relaxed cluster with two vacancies is 1448 kJ/mol compared with 1332 kJ/mol for the most stable arrangement.…”