Manifestation of strong d-p hybridization in photoluminescence spectra of ZnO:Ni and ZnO:Co

For the first time photoluminescence and photoluminescence excitation spectra for ZnO:Co and ZnO:Ni crystals were obtained at the excitation by the synchrotron radiation in the interval of energy of (3.7‐21) eV, T = 8 K. It is shown that these spectra are formed by intense radiative transitions through 3d charge transfer states in the band gap. This fact evidences about much stronger hybridization between d‐states of impurity and p‐states of anions in comparison with other II‐VI:3d compounds. It is very important for applications in optoelectronics, for visualization of ultraviolet radiation and understanding of photocatalytic activity of ZnO:3d nanocrystals in the visible region of the spectrum. From the comparison of PLE spectra for ZnO:Co and ZnO:Ni with the spectrum of calculated DOS for ZnO it is revealed a visible transformation of part of valence band states due to a strong d‐p hybridization. Obtained results allow us to consider ZnO:3d as a compounds with a strong correlations. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)