Binding energy and spectral width of Si 2p core excitons in SixGe1-x alloys.

Abstract

A calculation is presented to explain the anomalous experimental behavior of the Si 2p core-exciton binding energy and linewidth in ${\mathrm{Si}}_{\mathrm{x}}$${\mathrm{Ge}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$ alloys. The observed minimum in the line width near x\ensuremath{\simeq}0.15 can be explained as being the result of a competition between intrinsic broadening due to screening and extrinsic alloy broadening. For pure Si, the binding energy is estimated to be 0.15\ifmmode\pm\else\textpm\fi{}0.05 eV and the width is shown to be smaller that that observed at x\ensuremath{\simeq}0.15.