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Investigation study of Rare-Earth doped zinc oxide thin films produced via sol gel method
Dernière modification: 2017-11-20
Résumé
Zinc oxide thin films doped with rare-earth (Ytterbium) are deposited on glass substrates by sol gel (dip coating) technique, and then annealed them at 600C in vacuum, in order to investigate the insertion of Yb ions in the ZnO matrix and the related optical properties of the films. The dopping effect was investigated. The morphological, structural and optical properties were studied by Atomic force microscopy (AFM), X-ray diffraction techniques (XRD), Raman spectroscopy and UVvisible spectrophotometer. All samples showed hexagonal wurtzite structure with a preferential orientation along the (002) direction. We observed the average grain size of ZnO:Yb thin film to be in the range of 8-12 nm. We observed blue shift in the optical bandgap (3.22 eV to 3.25 eV) by increasing the Yb concentration (1 - 6 at.%), due to increasing the number of electrons, and replacing the di-valent (Zn2+) with tri-valent (Yb3+) dopants. Raman spectroscopy confirmed the results of XRD. The AFM images show that the roughness of the films has increased from 16 to 59 nm with an increase in the deposition time.