Nano-wire fabrication using anodic aluminum oxide as the template: Experimental studies of low-temperature anodization, electrodeposition and band gap measurement of cadmium sulfide nano-wires using resonance Raman spectroscopy

Anodization of aluminum in methanol solutions of {dollar}rm Hsb2SOsb4{dollar} at sub-zero temperatures (0{dollar}spcirc{dollar}C to {dollar}{lcub}-{rcub}80spcirc{dollar}C) has been studied for the first time. The resulting anodic aluminum oxide (AAO) films have uniform and regular pores whose diameters are significantly smaller than those found in AAO films anodized at room-to-zero-temperature. The sub-zero temperature was successfully achieved using a novel electolytic apparatus that utilizes temperature-controlled nitrogen cooling and 1.2 M {dollar}rm Hsb2SOsb4{dollar} in 3:1 (by volume) mixture of methanol and water as the electrolyte. At a constant anodization temperature of {dollar}{lcub}-{rcub}40spcirc{dollar}C, for example, the pores of the resulting AAO template were as small as 3.6 nm. Nonaqueous a.c. electrodeposition was then used to fabricate CdS nano-wires (of a mean diameter of 5 nm) by filling the pores of these AAO nano-templates with the semiconductor. Polarized Resonance Raman spectroscopy (RRS) was subsequently used to study these CdS nano-wire arrays.