Regularities of the Cd x Hg 1-x Te p-n junction formation by ion milling

Abstract

The main features of p-n conductivity type conversion by ion milling in vacancy-doped p-Cd x Hg 1-x Te are considered. A diffusion model of the Hg interstitials source formation in MCT crystals under IM was proved through investigation of conversion depth dependence on composition. The model explains, both quantitatively and qualitatively, conversion depth dependencies on the IM temperature and the alloy composition. The most important factor, which defines these dependencies, is an electric field located at the interface between the p-type defect layer and the n-type converted layer and in the grad band region. It was demonstrated that main features of carrier distribution over the p-n structure depth remained after 10 years samples storage. The relaxation of electrical properties of the n-layer main part after IM was explained by dissociation of donor complexes and centers formed by Hg interstitials with residual I and V group acceptor impurities. It was also demonstrated that IM results in forming a complex damaged n + -layer including several sub-layers with different nature of electron conductivity. An analysis of how electrons concentration relax in the n + -layer allows interpreting the nature of conductivity in one sub-layer through trapping mercury interstitials by dislocations and dislocation loops. The conductivity relaxation in this sub-layer occurs because the structure of such defects is rebuilt, with donor properties being lost.