Anodic oxidation of Al/Ge/Al multilayer films

We report the effect of an intermediate germanium layer on the process of anodic oxidation of an Al/Ge/Al multilayer film in oxalic acid solution and the morphology of the formed oxide membrane. The anodization of the upper and lower aluminum layers is performed in accordance with the classical mechanism of formation of porous anodic alumina and does not depend on the germanium layer. Whereas the anodization of the germanium layer is particularly sensitive to its structure and conductivity. In the case of amorphous germanium with low intrinsic conductivity, anodic dissolution of the layer is observed. A layer of porous germanium oxide is formed to occur from crystal germanium with high conductivity.