Study on Anodic Oxidation of Metals and Semiconductors by Electroluminescence Measurement

为了研究阳极氧化过程中金属和半导体的电致发光行为、阳极氧化膜的生长过程和缺陷结构之间的关系，以及检验电致发光现象作为一种表征阳极氧化膜的原位方法的可行性，对金属和半导体在阳极氧化过程中的电致发光进行了测量。测量电致发光强度的变化能够监测由于氯离子引起的SiO_2膜的击穿。在Na_2SO_4溶液中阳极氧化过程中从Nb观察到的电致发光与表面处理敏感相关。尤其是用砂纸对Nb表面进行机械抛光时，其电致发光强度最大。在Nb的阳极氧化过程中，残留在Nb表面的碳化硅等表面杂质成为电致发光的来源。这些结果表明，电致发光可以作为一种原位表征金属和半导体上的阳极氧化膜的方法。

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.