Effect of the elimination of the barrier layer period in productive process and its simulation of absorption spectra for anodic alumina membrane

An anodic alumina membrane is produced in two levels by performing the anodization process in various type of acidic electrolyte. Holes are characterized by hexagonal structure of varying diameters (from 40 to 420 nm). The heat and chemical stability as well as the regularity of the formed holes make the membranes appropriate for use in gas separating process, drug delivery and for fuel cell membrane applications. Detachment of the membrane from the aluminum base is the most important step in the membrane production process. In this research, initially, the synthesis of the aluminum based layer omitted the use of CuSO$_4$ and HCl. In the second step, the barrier layer at the end of the holes was removed via treatment with an aqueous phosphoric acid solution. The aim of this work is to analyze the effect of time upon the barrier layer removal process and, assuming that we have added gold to the alumina membrane, i.e. the alumina membrane has its empty pores filled with gold, simulations were done in order investigate its absorption spectra. Simulations were done using the FDTD method for all structures evaluated. The values for the structures' absorption and their spectra were calculated and plotted. In the case when the aluminum membrane pores are filled with gold, the curve of gold absorption spectrum has the highest absorption, so in practical terms, this means that making this membrane can have different applications.