Toward wafer-scale patterning of freestanding intermetallic nanowires

Abstract

Individual metal alloy nanowires of constant diameter and high aspect ratio havepreviously been self-assembled at selected locations on atomic force microscope (AFM)probes by the method reported in Yazdanpanah et al (2005 J. Appl. Phys. 98073510). This process relies on the room temperature crystallization of an orderedphase of silver–gallium. A parallel version of this method has been implementedin which a substrate, either an array of micromachined tips (similar to tips onAFM probes) or a lithographically patterned planar substrate, is brought intocontact with a continuous, nearly planar film of melted gallium. In several runs,freestanding wires are fabricated with diameters of 40–400 nm, lengths of 4–80 µm, growth ratesof 80–170 nm s − 1 and, most significantly, with yields of up to 97% in an array of 422 growth sites. Theseresults demonstrate the feasibility of developing a batch manufacturing process for thedecoration of wafers of AFM tips and other structures with selectively patternedfreestanding nanowires.