Many-particle effects in the optical spectrum of a semiconductor

Abstract

A local-orbital treatment of the two-particle Green's function for the electron-hole interaction is presented which takes into account both screened electron-hole attraction and its exchange counterpart. They give rise to the excitonic effects including Frenkel and intermediate coupling regimes and to the random-phase approximation local-field effects, respectively. An alternative formulation based on the Kohn-Sham density-functional scheme is also given and numerically tested. Quantitative calculations of the absorption and modulation spectra in Si show that electron-hole interaction effects significantly modify the absorption line shape and give rise to shifts of critical-point structure up to 0.2 eV. A model analysis indicates that deviations of the one-particle spectra of column IV, III-V, and II-VI semiconductors from experiment should similarly be accounted for.