On the application of positron spectroscopy to heteronanostrutures

The band structure calculations have been performed for the defect-free GaAS-AIAs superlattice and the electron-positron momentum density distributions have been computed. The comparison of data of calculations with the experimental ones obtained for GaAs and AIAs contituent materials by measuring the angular correlation of the annihilation radiation (ACAR) demonstrates good agreement. The possibility of a confinement of positron in the super lattice is predicted. The elemental specificity of the atomic environment of positron is shown to determine the electron-positron momentum region this distribution for a confined positron in GaAs-AIAs superlattice. In the high-momentum region this distribution is affected by the positron annihilation on the electrons in the shells of Ga3+ and Al3+ ion cores. The change of the position confined stated to the trapped one is considered as an example for the vacancy-type defects presents in GaAs constituent material. In this connection the non-destructive characterization of the heterostructures and superlattices by means of the positron self-seeking microprobe is shortly discussed.