Metallic nanowire synthesis by anodized aluminium oxide.
Yong, Ching Seng.
Date of Issue2009
School of Materials Science and Engineering
Anodic aluminium oxide (AAO) template synthesis is an electrochemical approach to fabricate metallic nanowires. Prior to anodization, the aluminum foil is electropolished in HClO4 (20 vol-%): CH3CH2OH (80 vol-%) solution to improve the aluminium foil morphology in order to obtain nanopore channels with good uniformity. Two-step anodization of aluminum foil is performed in 0.3M oxalic acid solution to produce AAO template with pore size of 60nm diameter and 3μm channel length, which dimension is suitable to deposit metallic nanowires. The aluminium substrate is then etched away in concentrated HgCl2 solution to separate out the AAO template. The AAO template undergoes pore-widening process by using H3PO4 (5 wt%) to remove the barrier oxide layer. The AAO templates are separated into two groups: one is deposited with 200nm of titanium/gold with sputtering/E-beam technique, and attached to ITO glass slides with silver paste; another group is attached directly to ITO glass slides with silver paste. With the template attached on the ITO glass slides, metallic (zinc) nanowire is deposited by carrying out wet electrodeposition using ZnSO4•7H2O (250g/l) solution. The characterization is done by using field-emission secondary electron microscope (FESEM). AAO template is successfully fabricated by skipping the heavy pretreatment process (such as annealing), and it is found out that the deposition of a metallic layer after barrier removal is still vital for successful electrodeposition.
Final Year Project (FYP)
Nanyang Technological University