Silver related emitting defects and aging ZnO nanocrystals

The emission, morphology, structure and chemical composition have been studied in Ag-doped ZnO nanocrystals (NCs) in as-grown state and after aging in ambient air by means of SEM, X-ray diffraction (XRD), photoluminescence (PL) and X-ray photo electronic spectroscopy (XPS) methods. PL spectra of as-grown Ag-doped ZnO NCs include a set of elementary PL bands: near band edge (NBE) emission, green and orange PL bands, as well as Ag related PL bands with the peaks at 2.68 and 2.89 eV. The PL intensity of Ag- related PL bands falls down at aging. Simultaneously, the PL intensity of orange PL band increases. Joint XRD analysis and PL study permit identifying the optical transition connected with the substitutional AgZn defects. At XPS research the variation of AgZn state and the formation of Ag oxide at aging has been revealed. The radiative defect transformations at aging have been analyzed and discussed.