Core excitons in semiconductors with a decaying core hole

Abstract

It is shown that deviations from static electronic screening, in addition to contributing an increase of the core-exciton binding energy EB, produce also a reduction of the core-exciton spectral width Γ as compared with the corresponding spectral width γ of the core hole alone. The occurence of this effect is interpreted as a fingerprint of dynamical screening since it cannot be obtained within the framework of a static theory. Numerical estimates for the Si 2p transition give about 70 meV for the difference γ-Γ, in qualitative agreement with experimental data.