Atomic force microscopy study of grain evolution during growth of thin oxide films

Atomic force microscope (AFM) was used to analyze the grain size of thin oxide films, formed at high temperatures on pure and CeO2 coated Ni. It has been found that there is a correlation between the grain size evolution and the mechanism of oxide growth. For both the pure NiO and the NiO modified by CeO2, formed by predominant Ni cation diffusion, the grain size increased continuously with oxide thickness and oxidation temperature. For NiO modified by CeO2 and formed by inward O anion diffusion, only small changes in grain size were observed in the range of the film thicknesses and oxidation temperatures studied. The evolution of grain size was compared with other parameters describing the morphology of the growth surface, such as vertical roughness. An example of application of the measured grain size to calculate the oxide growth rate is presented.