Papers by Keyword: Metal Organic Chemical Vapor Deposition

Abstract: Lithium Cobaltate (LiCoO₂) Films Were Prepared on the (001), (110), (110) and (112) Planes of Al₂O₃ Single Crystals Substrates by Metal Organic Chemical Vapor Deposition, and the Phases, Orientated Textures and Surface Morphologies Were Examined. (001)-Oriented LiCoO₂ Films Were Obtained on (001) and (110) Al₂O₃ Substrates, while (018)- and (104)-Oriented LiCoO₂ Films Were Grown on (110) and (112) Al₂O₃ Substrate. Triangular and Elongated Rectangular Faceted Structures Were Directionally Aligned, and (001)- and (018)-Oriented Grains Were Epitaxially Grown on (001) and (110) Al₂O₃ Substrates. Randomly Arranged Polygonal Faceted Structures Were Observed in the (001)-Oriented Licoo2 Film on (110) Al₂O₃ Substrate, while Locally Inhomogeneous Grains Were Observed in the (104)-Oriented LiCoO₂ Film on (1_,12) Al₂O₃ Substrate.

Abstract: GaN epilayers were grown on sapphire by metal-organic chemical vapor deposition (MOCVD), and the samples were annealed with rapid thermal processor (RTP) at 650, 750, 850 and 950oC, respectively. The effect of heat treatment on structural and optoelectronic properties of GaN epilayers was investigated. X-ray diffraction (XRD) analysis shows that the full width at half maximum (FWHM) of the rocking curves becomes smaller as the annealing temperature increases. Photoluminescence (PL) spectra at room temperature demonstrate that the yellow band decreases with the increase of annealing temperature. Hall-effect measurements reveal that carrier concentration of the GaN epilayers raise with the increase of annealing temperature. The results suggest that the structural and optoelectronic properties of GaN epilayers could be significantly improved by heat treatment.

Abstract: Functionally graded Ca-Ti-O/Ca-P-O films were prepared by MOCVD. The phases, composition and morphology of Ca-Ti-O and Ca-P-O films changed depending on the molar ratio of each precursors, total pressure (Ptot) and substrate temperature (Tsub). CaTiO3 films in a single phase were obtained at Tsub = 973 and 1073 K. CaTiO3 films prepared at 873 K had a dense and smooth surface, whereas that prepared at Tsub = 1073 K had complicated rough surface with a cauliflower-like texture. The graded texture of CaTiO3 films from columnar to fine grains was advantageous to good adherence for metal substrates. -TCP and HAp films in a single phase were obtained at Tsub = 973 and 1073 K. Both -TCP and HAp films had a dense and smooth surface. The maximum deposition rate of Ca-Ti-O and Ca-P-O films were 44 and 20 m/h, respectively, and several 10 times grater than that of sputtering method. Apatite formation rate strongly depended on the surface morphology of film. Apatite formed after 3 days on the CaTiO3 film, 14 days on the -TCP film and 6 hours on the HAp film in a Hanks’ solution.

Abstract: Ru-C nano-composite films were prepared by metal-organic chemical vapor deposition (MOCVD), and their microstructures and their electrode properties for oxygen gas sensors were investigated. Deposited films contained Ru particles of 5-20 nm in diameter dispersed in amorphous C matrix. The AC conductivities associating to the interface charge transfer between Ru-C composite electrode and YSZ electrolyte were 1000-10000 times higher than that of conventional paste-Pt electrodes. The electro-motive-force (emf) values of the oxygen gas concentration cell constructed from the nano-composite electrodes and YSZ electrolyte showed the Nernstian theoretical values at low temperatures around 500 K. The response time of the concentration cell at 500 K was 900 s.