University of Khartoum

Luminescence of alternating SiO2:Tb and SiO2:Ce thin films produced by sol-gel spin coating

Luminescence of alternating SiO2:Tb and SiO2:Ce thin films produced by sol-gel spin coating

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Title: Luminescence of alternating SiO2:Tb and SiO2:Ce thin films produced by sol-gel spin coating
Author: Seed Ahmeda, H.A.A.; Yousifa, A.; Swart, H.C.; Kroona, R.E.; W. D. Roos; Odireleng Martin Ntwaeaborwa
Abstract: Thin films of different numbers of SiO2:Tb layers as well as alternating layers of SiO2:Tb and SiO2:Ce were fabricated by the solgel spin coating method in order to study the effect of Ce3+ on the Tb3+ emission. The prepared films were annealed at 1000°C in a H2/Ar reducing atmosphere to prevent the occurrence of the tetravalent state of the Ce ions. The topography of the films was investigated by atomic force microscopy and small empty areas were detected which were confirmed by scanning electron microscopy. The luminescence intensity from Tb3+ was found to increase monotonically with the number of deposited layers up to sixteen layers. In the films consisting of alternating layers the Tb3+ ions could be excited through Ce3+ absorption as a result of energy transfer from Ce3+ to Tb3+ ions. When exciting the Tb3+ ions via the Ce3+ ion absorption wavelength of 320 nm, the green emission at 545 nm reached a maximum intensity for four double-layers and then decreased if more layers were added. 3D images obtained by time-of-flight secondary ion mass spectroscopy showed the influence of the heating process on the layers of the thin films.
URI: http://khartoumspace.uofk.edu/123456789/23461
Date: 2015


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