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Keywords:

  • oxygen doping;
  • II-VI semiconductors;
  • band-gap reduction;
  • oxygen pair;
  • first-principles calculation

Abstract

Oxygen doping into zinc-family II-VI semiconductors is studied by the first-principles calculation. We found that a large band-gap reduction occurs for ZnS and ZnSe, while there is little reduction and appears a deep level of oxygen in the band gap for ZnTe. It is shown that such difference reflects the order of energy positions of host cation (Zn) 4s-orbital and oxygen (O) 3s-orbital states. We also study the electronic states and stability of oxy-gen pair. By calculating the formation energy of O pair, we found that O dopants prefer to locate isolated. This is because O atom has so small radius that the pairing pro-motes a large elastic strain in host system, which feature is in contrast to the case of N pair in III-V systems.