Anodization Behavior of Al Film on Si Substrate With Different Interlayers for Preparing Si-Based Nanoporous Alumina Template

The fabrication and applications of porous anodic alumina (PAA) have been studied for decades. Recently, preparation of PAA template directly formed on Si has been developed to enhance the performance of the fabricated nanostructures. However, less attention is paid to the anodization mechanism of the Al film on the Si substrate. In the current study, the PAA template was fabricated on Si of which an interlayer was sandwiched between the Al film and the Si substrate. The anodization behavior of the Al film, especially at the alumina–substrate interface, was investigated through the observation of the variation of oxidation current and the structural change of alumina. Different degree of dissolution at the pore base of alumina was revealed when a different interlayer was introduced, leading to the formation of the arched pore bottom. At the same time, difference in the variation of current was also observed as the pore base reached the alumina–Si interface. These features were different from those observed in conventional anodization of Al foils. The findings in this study are of scientific and technological importance for the template-mediated growth of nanostructures, especially for those to be integrated into Si devices.