Aligned diamond nano-wires: Fabrication and characterisation for advanced applications in bio- and electrochemistry

Nano-wires have become promising tools in a vast field of applications. Due to the many unique properties of diamond, the use of diamond nano-wires in biosensors attracts increasing attention. In this paper we introduce the realisation of wires from diamond using self-aligned nickel nano-particles as etching mask in an oxygen ICP dry etching step. With this process it is possible to create wires of high aspect ratios of 50, with diameters as small as 20 nm, and typical lengths of up to 1 µm on a large area in a dense pattern of about 1011cm-2. The Ni nano-particles are formed by thermal annealing at 700 °C for 5 min of a thin (1 nm) Ni film that is deposited onto the diamond surface. The surface enhancement factor due to wires is dependent on the geometrical details of wires and was measured to be 10 to 80. The electrochemical properties of wires have been characterized by cyclic voltammetry using Fe(CN)6(exp -3/-4) which shows that such topographies act as filter for redox molecules