The electrical characteristics of porous Al2O3 produced by anodization

By anodizing at 20 C, current density 15 mA/sq cm, a thick porous layer, cell size 450-540 A, was produced above the 150-180 A nonporous barrier layer, total Al2O3 thickness 5-10 microns. Anodizing voltages were 15 or 20 V and times 3-75 min. Pore area density was 4.62 x 1010/sq cm. Cobalt atoms were deposited in the pores by anodizing in CoSO4. An Au counterelectrode was vacuum- evaporated on top of the porous Al2O3. Conduction processes observed in electrical experiments included Schottky-type behavior, field-ion diffusion, space- charge-limited currents, ohmic conductivity and also electroforming and electron emission. The calculated Al/Al2O3 Schottky emission typical barrier height was 1.11 eV; the space-charge-limited process activation energy was 0.50-0.68 eV. Electroforming was ascribed to field-induced growth of conducting filaments in porous regions previously developed by excess heat dissipation. 31 ref.--EPAA/AF.