Improving of Crystal Quality of Optical Computing Devices

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In this research, barium titanate thin films have been fabricated by the pulsed laser deposition method in order to investigate the effects of deposition conditions on the qualities of deposited films. Especially, effects of target preparation condition, the substrate temperature, the pressure of the ambient gases and so on have been investigated.A KrF excimer laser was used for the light source. The pressed powder and sintered targets were used. The temperature of the silicon substrate was raised and controlled by using an infrared heating unit. The qualities of the deposited film were characterized by means of the x-ray diffraction, the ellipsometry, and the scanning electron microscopy.As a result of the electron microscopy, it was found that the flatness of the films was strongly influenced by the laser fluence and flatness and smoothness of films could be improved by using the laser fluence of more than 5 J/cm^2 compared to the lower fluences which were conventionally used. From the results of the x-ray diffraction and ellipsometry, it was also found that the degree of crystallization of the film was strongly influenced by the substrate temperature and the crystalline film could be obtained at a temperature of more than 600 ℃.Besides above, new fabrication techniques of optical waveguides from the obtained films were also investigated. As a result, a new laser processing technique and a new photo-chemical vapor deposition technique have been established.