A New Electrochemical Lithography : Fabrication of Self-Organized Titania Nanostructures on Glass by Combined Anodization

Abstract

Self-organized anodic titania nanostructures (nanoporous films, nanodot, or nanorod arrays) were fabricated by a combined anodization from superimposed Al/Ti layers sputter-deposited on glass substrates. The specimens were first anodized in a constant potential mode to form nanoporous anodic alumina films with different pore sizes and intervals, which worked as electric filters and rendered a through-mask anodization to the underlying titanium layer on glass. In the successive anodization, either transparent nanoporous titania films with parallel cylindrical pores (ϕ20-40 nm, 50-75 nm interval, 980-1100 nm thick) or patterned titania nanoreliefs (quantum nanodot or nanorod arrays; ϕ20-100 nm, 30-260 nm, height, 50-380 nm interval) were fabricated on glass substrates, depending on the anodizing characteristics of titanium in different electrolytes. Particularly, X-ray photoelectron spectroscopy analysis suggested that the nanoporous anodic titania films were composed of titanium oxide (Ti-IV) and a small amount of titanium nitride (Ti-III) included with dissociated nitrogen. The transparent nanoporous titania films were amorphous in as-anodized state and transferred into polycrystalline tetragonal anatase after heating at 873 K, both exhibiting an elevated transmittance throughout the ultraviolet and visible light range. © 2005 The Electrochemical Society. All rights reserved.