Structural, electronic and optical properties of semiconducting rhenium silicide

Structural, electronic and optical properties of semiconducting rhenium silicide (ReSi 1.75 ) with various distributions of the silicon vacancies have been theoretically studied by means of ultrasoft pseudopotential and full-potential linearized augmented plane wave methods. We have found that the band dispersion is affected by vacancy positions, while the dielectric function and reflectivity display similar shapes for all considered variants, that can explain the rather scattered available experimental data on the gap value. Comparison between the calculated and ellipsometrically measured dielectric function and reflectivity on ReSi 1.8 polycrystals grown by the Czochralski technique shows a good agreement.