Structural and luminescence properties of yellow Y_3Al_5O_(12):Ce~(3+) thin-film phosphors prepared by pulsed laser deposition

摘要

Recently oxide phosphors have gained much attention because of the variety of materials available and chemical stability as compared to sulphide phosphors. Y_3Al_5O_(12):Ce~(3+) crystal is an excellent host material which is able to compatibly accept divalent and/or trivalent activators from both rare earth and transition metal groups. It is well known that YAG is a highly efficient yellow phosphor. However, these phosphors in the form of thin films have not yet been fully realized due to technical difficulties. We prepared thin-film-type YAG phosphors on silicon (110) substrate using a pulsed laser deposition technique. The luminescent and structural properties of thin-film phosphors were monitored as a function of key processing parameter which is the deposition temperature. The surface morphology of the grown thin films was strongly affected by the growth temperature. Electron diffraction spec-troscopy confirms the presence of the Y, Al, O and Si. Even though we could not obtain homogenous phases, by optimizing processing parameters, thin films with large homogenous areas and a high photoluminescence could be produced. XRD measurements revealed Y_3Al_5O_(12) structure when grown at temperatures from room temperature to 750 ℃; however, other phases such as Y_4Al_2O_9 and YAlO_3 are observed as impurities. The PL results, which are in good agreement with the XRD data, showed that Y_3Al_5O_(12) phase was relatively dominant in the film deposited at 750 ℃, so emission spectra are strong at around 570 nm.