Paper TF-ThP25
Flash Networking Poster: Surface Characterization and Luminescent Properties of Pulsed Laser Deposited Dysprosium-Doped Rare-Earth Oxyorthosilicates Thin Films

Thursday, October 22, 2015, 6:00 pm, Room Hall 3

Luminescent materials or phosphors have a wide range of technological applications in electronic information displays, solid state lighting, solar cells, advertising, medical imaging, etc. Although phosphors are usually used as powders, thin films have more advantages in many practical applications. We report luminescent properties and surface states of dysprosium (Dy³⁺)-doped lanthanum gadolinium oxyorthosilicate (La_2-xGd_xSiO₅:Dy³⁺; where x = 0, 0.5, 1.0, 1.5, 2) that were ablation deposited onto Si (111) substrates using the pulsed laser deposition (PLD) technique. Several deposition parameters were varied, including vacuum versus partial pressure of gas (O₂ or Ar), and substrate temperature using the 266 nm Nd: YAG excimer laser. The ablated targets were prepared from powders which were synthesized by combustion method. The films exhibited tunable and white photoluminescence emission when excited by either a monochromatized xenon lamp or a 325 nm HeCd laser in air at room temperature. The PL emission colour and the peak intensity were dependent on the ratio of La to Gd, concentration of Dy³⁺, and deposition conditions. Data from scanning electron microscopy (SEM) and atomic force microscopy (AFM) show that the major influence of the deposition conditions on the PL peak intensity was through changes in the morphology and topography of the films, which affects light scattering and out-coupling. The time-of-flight secondary ion mass spectroscopy (ToF-SIMS) was used to study the distribution of atomic and molecular ionic species on the surface of the films, while X-ray photoelectron spectroscopy (XPS) was used to analyse the chemical composition and electronic states of our samples.