The Change in Surface Structure of Alumina Thin Film Prepared by Sol-Gel Method

Abstract

The alumina thin films were prepared by the sol-gel method using a 1, 3-butanediol solution of aluminium nitrate. The film usually had a homogeneous flat surface. However, the surface structure of the film obtained after the immersion in a deionized water at 100°C changed to the sponze-like surface texture which was composed of fibrillay particles of 50W100 nm in length. The Al/Si intensity ratio of XRFS of the film surface decreased just after the immersion and then became roughly constant after the immersion of 2 h. Consequently, the change in the surface structure to the sponze-like texture was concluded to be due to 1)the partial dissolution of alumina particles from the substrate, and 2) the subsequent linkage between alumina particles which still remained to form stable fibrallars on the substrate. It was also found that the aluminium amount in the film can be controlled by the solution pH, temperature and the immersion time.