Study on Anodic Oxidation of Metals and Semiconductors by Electroluminescence Measurement

为了研究电致发光（EL）现象与阳极氧化膜的生长过程及其缺陷结构之间的关系，并检验EL现象作为阳极氧化膜原位表征方法的可行性，对金属和半导体在阳极氧化过程中的电致发光（EL）进行了测量。本文认为，从电致发光光谱中可以获得SiO_2中陷阱能级和SiO_2/Si界面电子结构的信息。通过测量电致发光强度的变化，可以监测到Cl ~-对SiO_2膜的破坏，Nb在Na_2SO_4溶液中阳极氧化时的电致发光与表面处理密切相关。特别是用金刚砂纸机械抛光Nb表面时，EL强度最大。Nb阳极氧化过程中残留在Nb表面的SiC等杂质成为电致发光源。这些结果表明，电致发光可作为金属和半导体阳极氧化膜的原位表征方法。

Measurements of electroluminescence (EL) from metals and semiconductors during anodic oxidation were carried out in order to investigate the relation between EL behaviors, growth processes of anodic oxide films, and their defective structures and to examine the availability of EL phenomena as an in-situ method for characterization of anodic oxide films.EL was observed from p-type Si during anodic oxidation in ethylene glycol solution of KNO_3. It is suggested that the information on trap levels in SiO_2 and electronic strucutre of SiO_2/Si interface is obtained from the EL spectra. The measurement of changes in EL intensity was capable of monitoring the breakdown of SiO_2 film due to Cl^- ions.EL observed from Nb during anodic oxidation in Na_2SO_4 solution depended sensitively on the surface treatments. Particularly, the mechanical polishing of Nb surface with emery papers gave the maximum EL intensity. The surface impurities remaining on the Nb surface such as SiC become EL sources during anodic oxidation of Nb.These results indicate that EL is useful as an in-situ method for characterization of anodic oxide films on metals and semiconductors.