AC-impedance measurements on porous aluminium oxide films

Abstract Porous aluminium oxide layers, prepared under different technical formation and sealing conditions, have been investigated by AC-impedance measurements in the frequency range 60 mHz ⩽ f ⩽ 65 kHz in 3.5 w% K 2 SO 4 solution. The results can approximately be described by a simple equivalent circuit characterizing the barrier- and porous-layer. It is demonstrated that variation of the formation-current density, as well as the sealing procedure, mainly affects the properties of the porous layer as indicated by characteristic changes of the dielectric constant and the specific resistivity.