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

目前的研究重点是通过金属-有机分子的反应控制来实现功能薄膜的晶化。通过对各种金属有机物的反应控制，合成了用于薄膜形成的金属-有机前驱体。采用红外光谱、核磁共振光谱等手段对前驱体在溶液中的结构进行了分析，并对前驱体薄膜的结晶行为进行了研究。研究发现，即使在铂/硅衬底上，焙烧条件也是促进钙钛矿型K(Ta，Nb)O_3薄膜晶化的重要因素。采用H_2O/O_2气相焙烧晶化法制备了K(Ta，Nb)O_3外延薄膜。X-射线极图测量证实了K(Ta，Nb)O_3薄膜在氧化镁和铂/氧化镁衬底上的外延生长。外延K(Ta，Nb)O_3薄膜的居里温度随Ta/Nb比的变化而变化，并受衬底应力的影响。利用金属-有机化合物的反应控制，在氧化镁衬底上生长了(Sr，Ba)Nb2O6和(PbBaNb2O6)外延薄膜。还解释了外延(Sr，Ba)Nb_2O_6薄膜与氧化镁衬底的关系。在透明衬底上制备了高度取向的β-BaB_2O_4薄膜。在1064 nm光的照射下，β-BaB_2O_4薄膜产生了二次谐波。基波与SH波之间的功率关系满足SHG理论。本课题论证了金属有机化合物反应控制对外延功能膜合成的重要性，并阐明了工艺条件与薄膜性能的关系。通过对金属有机化合物的反应控制，为高度取向的薄膜建立了铁电性和倍频等新的性质。

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.