Bordun I. Electronic excitation and luminescence of thin films based on yttrium oxide

The thesis is devoted to experimental investigation and theoretical explanation of optical and luminescence properties of Y2O3 thin films,both pure and doped with Eu3+. The structure, surface morphology and spectra of IR reflection of the thin films Y2O3:Eu – fused quartz (υ-SiO2) substrate system at 295 K in region 400 – 1600 cm–1 are measured. Light dispersion in Y2O3 thin films is studied and parameters of the three-parameter single oscillation model are determined. The shiff of the edge of fundamental absorption in Y2O3 thin films is explained by the Burstein-Moss effect. Varying of condition of receipt of thin-films of Y2O3 and use of Alentsev-Fock method shows that the spectrums of luminescence of thin-films of Y2O3 consist of row of bands of luminescence, that is recovered inter se, and their kind and quantity are determined by both the condition of receipt and excitation. The got results show connection of band of luminescence with a maximum in area of 3.40eV with luminescence of self-trapped exitons, bands with a maximum in area of 2.90 eV - with recombination of electrons with the holes, trapped on the centers predefined by an anionic sublattice, and bands with a maximum in area of 2.60 eV - with luminescence of associative donor-acceptor pair of Y3+-O2-. It is set that band of luminescence with a maximum in area of 4.20 eV more credible than all related to the admixtures or defects, and band of luminescence with a maximum in area of 3.20 eV not stoishometric is most probably predefined after oxygen. The time constant of decay luminescence in samples of Y2O3, obtained by discrete evaporation, which have by the most intensive photoluminescence, presents 111 mcs. The spectra and kinetics of the rise and decay of the cathodoluminescence of Y2O3:Eu thin films was investigated. Bused on the shape of the cathodoluminescence spectra at different excitation energies, showed the possibility of creating irregular solution of yttrium and europium oxide and the structural features of the surface and bulk layers. The time constant for the decay cathodoluminescence for 612 nm emission was determined and the value of whitch is within the range (1.8 – 4.1) ms. This value is a complex function of the typeof films deposition atmosphere, the activator concentration and duration of the exciting pulses was shown. The features of the risen cathodoluminescence and the proposal base on the delay rise cathodoluminescence analize structural perfection of thin films Y2O3:Eu. Based on the shape of the cathodoluminescence spectra at different concentration of the activator, showed the structural features of the small and large crystallites forming the film Y2O3:Eu.