Electronic structure of cationic core excitons in II–VI semiconductors

Abstract

The electronic structure of cationic core excitons in ZnS, ZnSe, ZnTe, and CdTe was analyzed by means of self-consistent-field multiple scattering Xα molecular cluster calculations. The exciton level introduced in the gap by the core hole is found to be weakly localized with a charge distribution similar to that of an isocoric single donor level. Core exciton binding and formation energies and also core ionization energies were calculated. The binding energies of the core excitons in ZnS are found to be almost independent of the depth of the core level involved. This behavior seems to be a general property of core excitons in semiconductors. Trends for core exciton binding energies, core level shifts and charge distributions are analyzed in the ZnX (X = S, Se, Te) series and also in CdTe.