N. Gaumer

Effect of compositional variation on optical and structure properties of europium-dopedSiO 2 -HfO 2 glasses

Glasses with compositions (100-x)SiO(2)-xHfO(2):0.3Eu(3+) (molar ratio, x=0,10,20,30) for optical applications were prepared using the sol-gel route. The introduction of hafnium into the glass matrix induced the energy splitting of the F27 state of Eu(3+) ions. Furthermore, fluorescence line narrowing (FLN) spectra indicated that Eu(3+) clustering occurred in glasses containing no hafnium. The addition of hafnium promoted better dispersion of Eu(3+) ions in the glass matrix. The role of hafnium on modifying the properties of glasses was discussed with respect to x-ray diffraction and FLN analysis.

Effect of CdS nanocrystals on the photoluminescence of Eu3+-doped silicophosphate sol gel glass

In this work, we investigate the effect of co-doping with CdS nanoparticles on the photoluminescence properties of Eu3+ doped silicophosphate glass prepared via the sol gel method. Infrared spectroscopy (FTIR) revealed the insertion of phosphorus within the silicate network. XRD and TEM analyses revealed the presence of CdS nanoparticles dispersed in the glass matrix. Based on the optical study and the effective mass theory for spherical quantum dots, it was found that CdS nanocrystals have a gap of nearly 3.53 eV and a size of 2.42 nm. The enhancement of Eu3+ emission induced by CdS nanocrystals and thermal annealing was assigned to either an energy transfer via defect states or structural alteration of the glass network around the rare earth ions.

Effect of roughness on third-order nonlinear-optical susceptibility of rare earth doped zinc oxide thin films

Zinc oxide (ZnO) and erbium doped zinc oxide (ZnO:Er) thin films, were deposited on heated glass substrates using spray pyrolysis technique. Third-order nonlinear-optical properties of ZnO and ZnO:Er have been investigated by the third harmonic generation (THG) method at the wavelength of 1064 nm using nanosecond Nd3+:YAG laser radiation. The dependence of third order nonlinear susceptibility and transmission characteristics on the thin film roughness has been measured. Third order nonlinear optical susceptibility ( chi(3)) values of the studied materials were in the remarkable range of 10-12 esu. The deposited films have been analyzed using X-ray diffraction (XRD) and atomic force microscopy (AFM).

Effect of substrate temperature on cathodoluminescence of ITO thin films prepared by spray pyrolysis

Highly conducting and transparent tin-doped indium oxide (ITO) thin films were deposited on glass substrates by spray pyrolysis. The characterisation of ITO thin films prepared under different deposition parameters is investigated. The transmission, resistivity and luminescence of the films were found to be strongly dependent on these parameters. The films prepared at the optimum conditions exhibit low resistivity and optical transmission larger than 90% in the visible region. ITO cathodoluminescence films prepared at 450degC and 500degC has been studied. These samples exhibit a strong luminescence peaks in visible region at 460 nm and 650 nm.

Europium-Doped Sol-Gel SiO2-Based Glasses: Effect of the Europium Source and Content, Magnesium Addition and Thermal Treatment on Their Photoluminescence Properties

Rare-earth doped silica-based glasses lead the optical materials due to their tailorable spectroscopic and optical properties. In this context, we took advantage of the sol-gel process to prepare various Eu-doped silica glasses to study their luminescent properties before and after annealing at 900 °C. The effect of magnesium on these properties was studied in comparison with Mg-free-glass. Using TEM, nitrogen sorption, XRD and FT-IR, we confirmed that the magnesium modifies the glass structure and the thermal treatment eliminates the aqueous environment, modifying the structure ordering. The emission spectra and the decay time curves show the advantages of the Mg addition and the annealing on the photoluminescent properties.

Physico-chemical characterization and study of nonlinear optical properties of tin and fluoride doped indium oxide thin films deposed by spray pyrolysis

The thin films of undoped oxide indium and doped oxide indium by fluorine and tin were prepared by SPRAY pyrolysis. These layers were deposited on glass substrates from the Indium chloride (InCl3), tin chloride (SnCl2;2H2O) and ammonium fluoride (NH4F).The microstructure, morphological, optical transmittance and chemical composition of these layers were studied by the X ray diffraction (XRD), the scanning electron microscopy(SEM), atomic force microscopy (AFM) and microanalysis (EDX) respectively. A study of luminescence by cathodoluminescence technique and a study of nonlinear susceptibility of the third order by the third harmonic generation (THG) technique of these thin films were carried out. The aim of our study is the optimization of luminescence as well as the non-linear response to a possible application in optoelectronics as transparent conductive electrode or in microelectronics fields.