2000 年 7 巻 286 号 p. 203-207
Carbonation of ZnO thin film was investigated in order to understand degradation of ZnO-based transparent conductive films, gas sensors and other electronic devices. The ZnO thin film (thickness : 400 nm) sputter-deposited on a glass substrate was exposed to the atmosphere of carbon dioxide (1.0×105 Pa) and saturated water vapor (2.3×103 Pa) at 20°C until 8 weeks when an exfoliation of the film occurred remarkably. The X-ray diffraction analysis showed a degradation of ZnO and formation of ZnCO3 and the basic carbonates. The crystal growth of ZnCO3 occurred independent of the orientation of the original ZnO crystal. Zn3CO3 (OH) 4·2H2O was detected in the early stage (1-2 weeks) and disappeared quickly. Zn3CO3 (OH) 4·2H2O was estimated to exist mainly at the surface of the film. Zn5 (CO3) 2 (OH) 6 and Zn2CO3 (OH) 2 increased during the present experiment. Zn2CO3 (OH) 2 was expected to exist mainly at the inner part of the film.