The effect of growth conditions and morphology on photoluminescence properties of Eu-doped ZnO nanostructures

• Effective role of defects on producing red emission at indirect excitation.
• Effect of synthesis temperature and gas ratio on increase of red emission intensity.
• Intrinsic defects mediated energy transfer to sensitize Eu3+ions.
• Decrease of red emission because of diminishing in oxygen vacancy.
• Eu3+ ions take a site with diverse symmetry in the ZnO host.

In this study un-doped and Eu-doped ZnO nanostructures were fabricated by Chemical Vapor Deposition (CVD) method. The effects of post annealing, synthesis temperature and morphology on structural and optical properties of Eu-doped ZnO were studied in detail. Prepared samples were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Photoluminescence Spectroscopy (PL) in fluorescence and phosphorescence modes. XRD results indicated that Eu ions were successfully doped into the ZnO Nanorods due to no diffraction peaks related to dopants in the XRD patterns. This study recommends that intrinsic defects have an effective roll on energy transfer (ET) to Eu ions at indirect excitation. The results also revealed significant improvement in crystal structure after annealing process due to decrease in surface defects. However, ET and red emission decreased because of diminution in oxygen vacancy. Study on the Eu-doped ZnO Nanorods sample indicated that increasing of surface area have a direct effect on producing intense red emission from Eu sites.

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