Alumina/Si interface of the Al-annealed sample. Cross-sectional SEM image of the interface PAA/Si of an Al-annealed sample at 500°C for 30 min in nitrogen gas. An undulation of the interface is depicted, attributed to Al diffusion into Si (due to the annealing) before anodization.
Gianneta et al. Nanoscale Research Letters 2013 8:71 doi:10.1186/1556-276X-8-71