Influence of anodizing voltage and electrolyte concentration on Al-1 wt% Si thin films anodized in H2SO4

Abstract

Porous anodic alumina (PAA) templates have been extensively studied due to their unique morphology and extensive applications. The fabrication of PAA can be modulated to achieve a self-ordered pore structure with desired pore size and interpore separation. PAA thin film templates were fabricated from silicon doped aluminum film, Al-1 wt% Si, based on one-step anodization method at 22 °C. Effects of anodizing potential (10–20 V) as well as sulfuric acid concentrations (0.6–1.8 M) on current density, interpore distance, anodization rate, and volume expansion were evaluated. The results indicated that current density increased largely exponentially with a concentration of the electrolyte at a given anodizing voltage. In addition, distinct and well-ordered pores were obtained for anodization conducted at 15 V and 20 V. The volume expansion factor is proportional to the applied voltage. At 1.8 M sulfuric acid, the expansion factor increases with pore regularity with 1.4 considered as the transition point. The minimum current density (2.1 ± 0.15 mA cm−2) was observed at the minimum anodizing condition (0.6 M, 10 V). Also, maximum anodizing condition (1.8 M, 20 V) resulted in the highest current density of 34 ± 4 mA cm−2. As expected, anodization time decreases with an increase in both anodization voltage and electrolyte concentration.