Control of nucleation site density of GaN nanowires

The control of nucleation site size and density for Au catalyst-driven growth of GaN nanowires is reported. By using initial Au film thicknesses of 15–50 A ° we have shown that annealing between 300 and 900 8C creates Au cluster size in the range 30–100 nm diameter with a cluster density from 300 to 3500 mm 2.Conventional optical lithography to create parallel Au stripes shoes that a minimum separation of 15 mm is needed to avoid overlap of wires onto neighboring lines with our growth conditions that yield wires of this same length. The GaN nanowires exhibit strong band-edge photoluminescence and total resistances of 1.2 108–5.5 106 V in the temperature range from 240 to 400 K, as determined for the temperature-dependent current–voltage characteristics