Mesurement of Passive Film Growth and Breakdown, and Excitation of Local Phenomena on Electrode By Using Electrochemical AFM・STM

本研究将原位电化学AFM/STM技术应用于钝化金属表面，为钝化膜的形成、生长和击穿等电极过程的分析提供有价值的信息。研究了电极上局部电化学过程的微改性和激发。(1)采用原位电化学原子力显微镜对溅射到石英玻璃上的Ti膜电极、Ti板电极和Al电极进行了原位电化学原子力显微镜的研究，观察了极化条件下钝化膜的生长和击穿过程。对于Ti薄膜的微结晶过程，发现在薄膜生长过程中由于非常高的电场，导致氧化表面的表面粗糙化，称为钝化膜的击穿。(2)采用电化学隧道光谱技术对Fe和Ti表面形成的钝化膜进行了电子性能研究。研究了电化学系统中势垒形状随电位扫描的变化规律，以及尖端电极对半导体电极空间电荷层极化条件的影响。(3)利用原子力显微镜观察了碳钢在活性溶解过程中的表面形貌变化。结果与扫描电镜和激光共焦显微镜所获得的图像进行了比较。从碳钢中珠光体组织的角度讨论了腐蚀过程。(4)采用原子力显微镜尖端对阳极氧化膜生长后的铝表面进行微改性。然而，修改后的针尖受到机械损伤，导致观察到的AFM图像退化。为此目的，需要开发更复杂的改性技术。

In this research in-situ electrochemical AFM/STM technique was applied to passivated metal surface to obtain valuable information for analysis of electrode process such as passive film formation and growth, and breakdown. Micro-modification and excitation of local electrochemical process on electrodes were also aimed. (1) In-situ electrochemical AFM was applied to Ti film electrode sputtered onto quartz glass, Ti plate electrode, and Al electrode to observe growth and breakdown processes of the passive film under polarization condition. For Ti film proceeding of micro-crystallization due to very high electric field during film growth was found, resulting in surface roughening of the oxide surface, known as breakdown of the passive film. (2) Electrochemical tunneling spectroscopy technique was applied to the passive films formed on Fe and Ti to investigate their electronic properties. Tunneling barrier shape as a function of potential scanning in the electrochemical system, and effect of tip electrode on polarization condition through the space charge layr in the semiconductive electrode were evaluated. (3) Morphological change of corbon steel surface during active dissolution was observed by AFM.Results were compared with images obtained by SEM and conforcal laser microscopy. Corroding process was discussed concerning with the pearlite structure in the carbon steel. (4) AFM tip was used to achieve micro-modification of Al surface after anodic oxide film growth. After modification, however, tip was mechanically damaged resulting in degradation of AFM image observed. For such purpose development of more sophisticated technique for modification is required.