Focused-ion-beam platinum nanopatterning for GaN nanowires: Ohmic contacts and patterned growth

Nanopatterned Pt by Ga+ focused ion beam (FIB) decomposition of an organometallic precursor forms low resistance ohmic contacts on 40-70 nm diameter GaN nanowires (NWs) grown by thermal reaction of Ga2 O3 and N H3. With no intentional doping, the wires are presumed to be n type. Thus, the linear I-V behavior is surprising since evaporated Pt usually forms Schottky barriers on n GaN. Ohmic behavior was not obtained for 130-140 diameter wires, even with thicker Pt contacts. A second application of FIB Pt nanopatterning was demonstrated by position-selective growth of GaN NWs on Pt catalyst dots. NW locations and density are defined by the position, size, and thickness of the Pt deposit. Combining these techniques provides a versatile platform for nanostructure research and development.