Nadine Geyer, Zhipeng Huang, Peter Werner
For nanowires with a diameter below 20 nm we developed the following fabrication method: combining prepatterning the substrate by anodic aluminum oxid masks (AAO) (Figure 1a), reactive ion etching (Figure 1b), metal deposition (Figure 1c) and metal-assisted wet chemical etching (Figure 1d) this method generates large areas of highly ordered nanowires with diameters ranging from 10 to 50 nm.
Fig 1: Schematic diagram of the fabrication of nanowires with sub-20 nm diameter. a) An AAO mask is used for templating the substrate. b) RIE through the AAO pores was carried out for the etching of small pits into the surface of the substrate. c) The AAO mask was removed chemically and a thin metal layer was deposited on the patterned substrate. d) The metal-assisted chemical wet etching is carried out using HF/H2O2 as the etching solution. Afterwards, the metal layer was removed and only the nanowires remain.
Fig. 2: SEM image of an AAO mask after reactive ion etching (left) and of metal-assisted chemical etched Si nanowires with an average diameter of 20 nm (right).