Open AccessEffects of Fe doping on the crystal structures and photoluminescences of ZnO: Ni thin films prepared by sol-gel method
Author(s) -
Wu Zhong-Hao,
Ming Xu,
Duan Wen-Qian
Publication year - 2012
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.61.137502
Subject(s) - materials science , photoluminescence , doping , vacancy defect , x ray photoelectron spectroscopy , zinc , analytical chemistry (journal) , ultraviolet , thin film , scanning electron microscope , crystal (programming language) , exciton , valence (chemistry) , crystallography , nanotechnology , optoelectronics , chemical engineering , condensed matter physics , metallurgy , chemistry , programming language , computer science , engineering , physics , organic chemistry , chromatography , composite material
Zn0.95-xNi0.05FexO (x=0, 0.005, 0.01, 0.03, 0.05) thin films are fabricated on the glass substrates by the sol-gel method. The surface morphologies and crystal structures of the films are investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results reveal that preferential orientations are all along the (002) direction in all films. the qualities of ZnO: Ni films for low or high Fe concentration become worse, the crystal grain sizes of ZnO: Ni film are reduced, but moderate Fe doping seems to improve the film quality. XPS results reveal that Ni elements exist as Ni2+, and Fe elements exist as Fe2+ and Fe3+. Strong ultraviolet emission peaks, blue double emission peaks and green emission peaks are observed in the photoluminescence spectra of all samples at room temperature. It is found that the PL intensities of (Ni, Fe) co-doped ZnO films could be well modulated by Fe doping. In combination with other reports, we think that the ultraviolet emission peaks are due to exciton recombination; while the blue double peaks are caused by transition of electrons from the zinc interstitial to the top of the valence band or from the oxygen vacancy to the zinc vacancy. However, the green peak is highly dependent on oxygen vacancy and zinc vacancy formed by doping.