Keywords: band structure, charge density, positron annihilation, momentum density, independent particle model, empirical pseudopotential method, zinc selenide, zinc sulfide, zinc telluride, semiconductor compounds
Study on momentum density in semiconductor compounds ZnS, ZnSe and ZnTe by positron annihilation
The independent particle model (IPM) coupled with empirical pseudopotential method (EPM) was used to compute the thermalised positron charge densities in specific family of binary tetrahedrally coordinated crystals of formula ANB8?N . Initial results show a clear asymmetrical positron charge distribution relative to the bond centre. It is observed that the positron density is maximum in the open interstices and is excluded not only, from the ion cores but also to a considerable degree from the valence bonds. Electron-positron momentum densities are calculated for the (001, 110) planes. The results are used to analyse the positron effects in ZnS, ZnSe and ZnTe. Our computational technique provides the theoretical means of interpreting the k-space densities obtained experimentally using the two-dimensional angular correlation of annihilation radiation (2D-ACAR).