Oscillatory kinetics of anodic oxidation of silicon – influence of the crystallographic orientation

This work describes the oscillatory kinetics of the anodic oxide growth on silicon with crystallographic orientations (1 1 1) and (1 0 0). Although the oscillations are observed for two orientations if the experimental variables are properly chosen, their shape, amplitude and period are essentially different. It is shown that the oscillations are caused by a continuous growth of thin oxide layers at the sample surface and their peeling off.An analysis of the morphology of the samples and their kinetics of growth shows that the oscillatory anodization kinetics is a self-organizing phenomenon emerging as a result of collective interactions in the electrolyte/Si system. These interactions are influenced by the crystallography of silicon. The case of (1 1 1) Si shows the presence of the correlation links in a sequence of individual oscillations nearly two times longer than in the case of (1 0 0) Si . These differences are attributed to different mechanisms of the pore formation in (1 1 1) and (1 0 0) silicon wafers.