INSTITUTE OF PHYSICS PUBLISHING NANOTECHNOLOGY Nanotechnology 16 (2005) 2275–2281 doi:10.1088/0957-4484/16/10/049 Fabrication of gold nanorod arrays by templating from porous alumina Dusan Losic 1,2,3 , Joe G Shapter 1 , James G Mitchell 2 and Nicolas H Voelcker 1,3 1 School of Chemistry, Physics and Earth Sciences, Flinders University, GPO Box 2100, Adelaide 5001, Australia 2 School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide 5001, Australia Received 3 June 2005, in final form 2 August 2005 Published 26 August 2005 Online at stacks.iop.org/Nano/16/2275 Abstract A simple procedure for fabrication of gold films with nanorod arrays is described. The method is based on thermal evaporation of gold onto a porous alumina (PA) membrane used as a template. The gold films were obtained after removing the template and characterized using scanning electron microscopy, atomic force microscopy and ultraviolet–visible spectrophotometry. The prepared gold films are composed of arrays of sharp (<20 nm at apex) rod-shaped gold nanostructures. These structures closely follow the organization and distribution of pores of the PA template. The length of the gold nanostructures is estimated to range from 300 nm to more than 1000 nm. It was found that their length is influenced by the size of the pores in the PA and the temperature of the PA during gold evaporation. Spectrophotometric characterization shows that the prepared gold films exhibit a surface plasmon resonance absorption peak located between 525 and 540 nm. (Some figures in this article are in colour only in the electronic version) 1. Introduction Fabrication of nanostructured materials is an exciting area of current research across many disciplines. Considerable interest has been aroused in the fabrication of noble-metal materials structured on the nanoscale, not only in fundamental studies, but also for various industrial and technological applications [1]. In particular, development of sensing devices utilizing localized surface plasmon resonance (SPR) exhibited by nanopatterned gold structures has been attractive [2–4]. The fabrication of nanostructured gold substrates in several forms including bulk structures, thin films and particles has been reported [5, 6]. From these preparations, unique optical, electrochemical and catalytic properties have been demonstrated [2, 3, 7, 8]. Recent studies have shown that nanoscale structures made of gold offer great potential for application in optoelectronics, chemosensing, biosensing, and catalysis [1, 3, 8–11]. Several strategies have been used for the fabrication of nanostructured gold films (or other metals), which include 3 Authors to whom any correspondence should be addressed. electron-beam lithography, laser ablation, scanning probe microscopy, template synthesis, self-assembly and selective etching [12–17]. Among these, template synthesis, in particular using porous alumina (PA), has been one of the most popular methods, enabling fabrication of a variety of nanoscale materials such as metals, semiconductors, metal oxides, carbon nanotubes and polymers [4, 13, 18–21]. Gold structures with different nanoscale 2D and 3D geometries including pores, wires, rods, tips, tubes, rings and particles have been fabricated [4, 9, 18, 21–26] in a low cost, reliable and versatile process that allows for mass production without using expensive lithographical or nanomanipulation tools [13–15]. PA membranes provide a well-ordered array of straight pores with well-defined diameters from tens of nanometres to several microns easily controllable by adjusting the etching conditions [18, 27, 28]. These membranes can serve as scaffolds for gold deposition and pattern transfer into the resulting gold film or particle dispersions [4, 22, 26]. Electroless and electrochemical deposition are currently the predominant methods for the deposition of gold into pores of a PA template [18, 22, 25, 26]. These methods 0957-4484/05/102275+07$30.00 © 2005 IOP Publishing Ltd Printed in the UK 2275