STRONG-COUPLING OF NI DONOR EXCITATIONS WITH LOCALIZED VIBRATIONS IN THE SEMICONDUCTORS ZNSE-NI AND ZNO-NI

The electroabsorption spectra within the range of nickel donor exciton s in the semiconductors ZnSe:Ni and ZnO:Ni are presented. The defect v ibrations in a crystal of ZnSe:Ni induced by Ni impurity ions having a charge state of + 1 with respect to the lattice are described. The ca lculations have been carried out in the framework of a recursive schem e in a shell model. Model calculations have enabled an interpretation of the vibronic structure in the electroabsorption spectra of Ni donor excitons in crystals of ZnSe:Ni and ZnO:Ni. The most intense vibratio nal replicas of the Ni donor exciton zero-phonon line appears to have a combination character omega(II) + n omega(I). (C) 1998 Elsevier Scie nce B.V. All rights reserved.