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The purpose of this study was to identify and correlate the microstructural and luminescence properties of europiumdoped Y 2 O 3 (Y 1-x Eu x ) 2 O 3 thin films deposited by metallorganic chemical vapor deposition (MOCVD), as a function of deposition time and temperature. The influence of deposition parameters on the crystallite size and microstructural morphology were examined, as well as the influence of these parameters on the photoluminescence emission spectra. (Y 1-x -Eu x ) 2 O 3 thin films were deposited onto (111) silicon and (001) sapphire substrates by MOCVD. The films were grown by reacting yttrium and europium tris(2,2,6,6-tetramethyl-3,5heptanedionate) precursors with an oxygen atmosphere at low pressures (5 torr (1.7 ؋ 10 3 Pa)) and low substrate temperatures (500°-700°C). The films deposited at 500°C were smooth and composed of nanocrystalline regions of cubic Y 2 O 3 , grown in a textured [100] or [110] orientation to the substrate surface. Films deposited at 600°C developed, with increasing deposition time, from a flat, nanocrystalline morphology into a platelike growth morphology with [111] orientation. Monoclinic (Y 1-x -Eu x ) 2 O 3 was observed in the photoluminescence emission spectra for all deposition temperatures. The increase in photoluminescence emission intensity with increasing postdeposition annealing temperature was attributed to the surface/grain boundary area-reduction effect.

Thin films of (Y 0.92 Eu 0.08 ) 2 O 3 were synthesized through chemical vapor deposition of b-diketonate precursors onto glass and sapphire substrates. The films were weakly luminescent in the as-deposited condition and were composed of spherical particles 3 mm in diameter. A KrF laser was pulsed for 25 ns from 1-3 times on the surface of the films. One pulse was sufficient to melt the film and repeated pulses caused ablation of the material. Melting of the film smoothed the surface, increased the density, and increased the photoluminescent emission intensity.When a high intensity ultraviolet (UV), pulsed photon beam is absorbed by the surface of a material, the transfer of energy produces a high local temperature. This can be used to melt and subsequently solidify the irradiated area and/or to simply alter the surface structure of the solid. The transfer of UV laser energy into the surface of a solid is the basis a nonconventional processing technique called pulsed laser melting that has been developed for rapid melting and subsequent crystallization of semiconductors. Pulsed excimer lasers have been used to crystallize amorphous lead titanate films 1 and amorphous semiconductors 2-5 induce grain growth in silicon through melting and solidification, 6 and to clean and smooth the surfaces of materials. 7 Phosphors are inorganic solids that emit light when excited with an external energy source such as high energy photons, electrons, or an electric field. Europium doped yttrium oxide [Y 2 O 3 : Eu 31 or (Y 12x Eu x ) 2 O 3 , x < 0.10] is a well-known photo-and cathodoluminescent phosphor used in the lighting industry and in cathode ray tube displays. The material luminesces a red/orange color (peak wavelength 611 nm) when excited by high energy photons or electrons. The luminescence arises from the 4f ! 4f electronic transitions of the Eu 31 ion.For flat panel display applications, thinner phosphor screens are required in order to increase light transmission (to the viewer), improve spatial resolution, reduce saturation effects, and reduce the cost. However, low temperature thin-film deposition techniques (e.g., sputtering, evaporation, chemical vapor deposition, laser ablation, etc.) typically produce amorphous or poorly crystalline films that require high temperature annealing to optimize the luminous efficiency. It is well documented that an increase in processing or postsynthesis annealing temperature increases the luminescent efficiency of Y 2 O 3 : Eu 31 . 8 Unfortunately, these temperatures are higher than the use temperature of low-cost glass (e.g., Corning 7059 which has a strain point of 2600 ± C), a desirable substrate from a manufacturing point of view. This is a major stumbling point in utilizing thin-film phospors.Thermal processing by laser treatment has many advantages over standard heat treatment methods. For example, the substrate is not exposed to elevated temperatures that can cause chemical reactions between the substrate and film or cause degradation of the substrate. Additionally, the proces...

Fine-particle-size (1-2 m), europium-activated strontium thiogallate phosphors, Sr 1Ϫx Eu x Ga 2 S 4 , have been synthesized by a novel, solid-state, rapid metathesis reaction with metal chloride and sodium sulfide precursor powders. The reaction was initiated in an agate crucible with a heated tungsten filament in a glove box. The resultant powders were weakly crystalline and not luminescent in the as-synthesized state. Subsequent heat-treatment in a N 2 atmosphere for 4 h at 750ЊC fully crystallized the powders and produced the characteristic photoluminescence broad-band emission centered at 535 nm of Sr 1Ϫx Eu x Ga 2 S 4 .