Studies on crystallization of functionality thin films through reaction control of metal-organic molecules

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The current research project focuses on the crystallization of functionality thin films through reaction control of metal-organic molecules. Metal-organic precursors for thin film formation were synthesized by reaction control of various metallorganics. The structure of the precursor in solution were analyzed by various spectroscopic methods, such as IR and NMR.The crystallization behavior of precursor films were investigated. The calcination conditions were found to be an important key for promotion of the crystallization of perovskite K (Ta, Nb) O_3 film even on Pt/Si substrates. Epitaxial K (Ta, Nb) O_3 films were successfully crystallized on MgO and Pt/MgO using H_2O/O_2 vapor calcination followed by crystallization. The epitaxy of K (Ta, Nb) O_3 film on MgO and Pt/MgO substrates was confirmed by X-ray pole figure measurement. The Curie temperatures of epitaxial K (Ta, Nb) O_3 films varied with the Ta/Nb ratios, and were affected by the stress from the substrates. Epitaxial (Sr, Ba) Nb_2O_6 and (Pb, Ba) Nb_2O_6 thin films were found to crystallize on MgO substrates using the reaction control of metal-organic compounds. The relation between epitaxial (Sr, Ba) Nb_2O_6 film and MgO substrates were also explained. Highly oriented beta-BaB_2O_4 thin films were synthesized on transparent substrates. beta-BaB_2O_4 thin films were found to generate second harmonic (SH) wave on irradiation with 1064 nm light. The power relation between the fundamental and the SH wave satisfied the theory of SHG.The present project demonstrated the importance of the reaction control of metal-organic compounds for the synthesis of epitaxial functionality films, and clarified the relation between the processing conditions and the properties of the films. The new properties of the films, such as ferroelectricity and SHG,were established for the highly oriented films through reaction control of metal-organic compounds.