Fabrication of nanorods by metal evaporation inside the pores of ultra-thin porous aluminatemplates

Abstract

Porous alumina has attracted a great deal of attention as a template material for thegrowth of nanowires and nanodots. Typically, the pores have a high aspect ratio, whichforbids the use of evaporation techniques for filling them, due to a pore closureeffect. For this reason electrochemical methods are mainly used. However, thereare materials, such as Al, which are very difficult to deposit electrochemically.In this work, the fabrication of Al nanorods by electron gun evaporation intolow aspect-ratio pores of ultra-thin porous alumina templates is described. Thethicknesses of the templates are in the range from 50 to 70 nm, while their pores havediameters from 20 to 40 nm, i.e. their diameter:height aspect ratios are very low, from1:1.5 to 1:3. These properties make it possible to completely fill the pores withevaporation techniques. This method can be generalized to any target and substratematerial.