Comparative Study of Pore Characterizations of Anodized Al–0.5 wt.% Cu Thin Films in Oxalic and Phosphoric Acids

Abstract

Porous anodic alumina (PAA) thin films, having interconnected pores, were fabricated from Cu-doped aluminum films deposited on [Formula: see text]-type silicon wafers by anodization. The anodization was done at four different anodizing voltages (60[Formula: see text]V, 70[Formula: see text]V, 80[Formula: see text]V and 90[Formula: see text]V) in phosphoric acid and two voltages (60[Formula: see text]V and 70[Formula: see text]V) in oxalic acid. The aluminum and PAA samples were characterized by SEM and XRD while the pore arrangement, pore density, pore diameter, pore circularity and pore regularity were also analyzed. XRD spectra confirmed the aluminum to be crystalline with the dominant plane being (220), the Cu-rich phase have an average particle size of [Formula: see text][Formula: see text]nm uniformly distributed within the Al matrix of 0.4-[Formula: see text]m grain size. The steady-state current density through the anodization increased by 117% and 49% for oxalic and phosphoric acids, respectively, for 10[Formula: see text]V increase (from 60 to 70 V) in anodization voltage. Similarly, the etching rate increased by 100% for oxalic acid and by 40% for phosphoric acid which are responsible for 47% and 29% decreases in anodization duration, respectively. The highest value of circularity obtained for anodized Al–0.5[Formula: see text]wt.% Cu formed in oxalic acid at 60[Formula: see text]V was 0.86, and it was 0.80 for the phosphoric acid at 90[Formula: see text]V. Anodization of Al–0.5[Formula: see text]wt.% Cu films allows the formation of circular pores directly on [Formula: see text]-type silicon wafers which is of importance for future nanofabrication of advanced electronics. The results of anodized Al–0.5[Formula: see text]wt.% Cu thin film were compared with other anodized systems such as anodized pure Al and Al doped with Si.