Physical Properties of Granular Metal Films and Their Applications for Electronic Devices

Pt/SiO_2颗粒金属膜的电子输运性质研究了中间金属含量（40%）的颗粒金属的电导率随温度的变化关系。当薄膜厚度足够薄时，在低温区观察到由安德森局域化引起的金属-绝缘体转变。由于弱安德森局域化的存在，这种转变随膜厚的增加而受到干扰。光化学能量转换颗粒金属膜被用来稳定半导体电极，用于水的光电解。系统地研究了Pt/TiO_2颗粒膜电极的光电化学性能，结果表明：Pt/TiO_2颗粒膜电极的光电化学性能明显提高，电极的水分解反应效率明显提高。颗粒膜气敏元件Pt/TiO_2颗粒膜的电阻率受环境气体的影响很大：引入氢气使电阻率降低，引入氧气使电阻率升高。复合氧化物膜研究了由各种金属组成的二元和三元氧化物膜。根据薄膜的红外吸收光谱的研究，复合氧化物的晶体学优选结构是氧盐或双氧化物，取决于金属的相对离子半径。用各种方法制备了分散在绝缘膜中的半导体微粒。在Si/SiO_2颗粒半导体系统中观察到了光吸收谱的一些反常现象以及吸收边的蓝移。

Electronic Transport Properties of Pt/SiO_2 Granular Metal FilmsTemperature dependence of the electrical conductivity of granular metals with intermediate metal contents( 40%) were investigated. Metal-insulator transition due to the Anderson localization was observed at low temperature region when the film thickness was thin enough. The transition was disturbed with increasing film thickness because of weakend Anderson Localization.Photo-Chemical Energy ConversionGranular metal films were utilized for stabilizing semiconductor electrodes for the photoelectrolysis of water. Systematic studies on the photoelectrochemical properties of the granular metal-coated Si electrodes revealed that the efficiency of the water decomposition reaction was improved signifcantly by the coating.Granular-Film Gas SensorThe electrical resistivity of Pt/TiO_2 granular metal films was found to be influenced strongly by ambient gases: The resistivity decreases by introducing hydrogen, whereas it increased by introducing oxygen. The sensitivities were dependent upon the metal fraction in the granular metal films.Complex Oxide FilmsBinary and ternary oxide films composed of various metas were investigated. According to the studies of infrared absorption spectra of the films, crystallographically preferable structure of the complex oxides was either an oxy-salt or a double oxide depending upon the relative ionic radii of the metals.Granular SemiconductorsThe granular nature was extended to semiconductor-insulator composite systems. Semiconducting fine particles dispersed in insulator films were tried to be fabricated with various methods. Some anomalies in optical absorption spectra as well as the blue-shift in the absorption edge were noted in a Si/SiO_2 granular semiconductor system.