Synthesis And Characterization Of Rare-earth Doped SiC_xN_y Films

SiCN is a novel silicon based photoelectric material, Rare earth doped and undoped SiCN films were prepared and investigated.(1) SiCxNy films were prepared on Si substrates by rf sputtering, and the structures, compositions, and chemical bonds were investigated by XRD, FTIR, and XPS. The results have demonstrated that the room-temperature deposited SiCN films were amorphous, containing a network of Si-C, Si-N, and C-N bonds. The ratio of constituents of the three elements (Si, C, and N) in the films can be tuned by the partial pressure ratios of N2/Ar, the substrate temperatures, and sputtering powers, and this type of change in the compositions change the optical properties of thin films. While, when the temperature increase up to 800℃, the films will contain some crystalling components of SiCxNy with a coarse surface. The films show a good properties of electroluminescence (EL).(2) The preparation and properties of of SiCN-film-based EL devices were investigated by using a ITO/SiCN/Al sandwich structure. The effect of the partial pressure ratios of N2 on the electronic and luminescent properties of the devices were disscused. The results have demostrated that the devices changed from bidirectional to unilateral, even Insulating, accompanying with the EL changing from a bidirectional luminscence to an unilateral one, finally a non-luminous one. A model were proposed to illuminestrate this phenomenon. The investigation demostrated that SiCxNy shows a broad luminescent band ranging from 400-700nm due to the Complex network structure.(3) The preparation, post-treatment, and photoluminescence (PL) properties of rare earth doped SiCN films were investigated. Two types of Tb-doped SiCN films were deposited by cosputtering of Tb flake and SiC target under N2 and NH3 ambience. The prepared Tb-doped samples show a good green light emission. The annealing treatment under different temperatures and gas ambiences have indicated that the samples treated under NH3 ambience at 800℃and show the strongest visible green light emission, and the samples annealed in air at only 700℃show the strongest ones.However, the samples treated under carbothermal ambience at 800℃show the best PL behaviour. Once the annealing temperature increase up to 1250℃, the films will decomposited into SiC nanocrystal and other nanoclusters. Furthermore, the mechanism of the decomposition of the samples and energy transfer of PL were discussed by using XRD, IR, XPS, PL, and PLE.