Fabrication of gold nanotip arrays using anodic aluminium oxide (AAO) template

Abstract

Recently, the nanotip arrays are widely researched on due to its wide application in nano-electronics, field emission, sensors and etc. They are usually fabricated by a combination of DRIE (Dry-Reactive-Ion-etching) and FIB (Focused-Ion-Beam) processes. However these processes require many fabrication steps, are high in cost and are limited in material choices. Therefore a new methodology for producing the nanotip arrays based on manipulating the nanopores size in the AAO channel was introduced.

AAO nanotip arrays template are successfully fabricated using a combination of two-step anodization followed by multi-step anodization in a three-acids electrolyte solutions (sulphuric, oxalic and phosphoric acid), two-acids electrolyte solutions (sulphuric and phosphoric acid) or single-acid electrolyte solution (phosphoric acid).

The insulating barrier layer (BLA) must be first removed before material can be deposited into the nanotip arrays template. Chemical etching with HgCl2 and H3PO4 produces an open-through AAO nanotip arrays template without over-compromising the nanotip structure due to the thick apex tip region acting as a protection layer.

Gold nanotip arrays are investigated in this study. Gold is electro-deposited into the open-through AAO nanotip array template. However, due to insufficient deposition time, gold nanorods arrays is obtained instead of gold nanotips arrays.