Electron transport properties of individual gallium nitride nanowire decorated with gold nanoparticles

Variations in the electron transport properties of individual n-type gallium nitride (n-GaN) nannowires decorated with gold (Au) nanoparticles as a function of nanowire diameter (~50nm - 400nm) have been studied. GaN nanowires were grown by vapor-liquid-solid (VLS) process and single nanowire devices were fabricated by photolithography techniques. Gold nanoparticle (~5nm-10nm) decoration was achieved by plasma enhanced chemical vapor deposition (PECVD). Two orders of magnitude drop of the current in gold decorated GaN nanowires compared to the bare GaN nanowires were observed. This effect is attributed to carrier depletion formed at the n-GaN nanowire/Au nanoparticle interface due to the formation of a metal-semiconductor Schottky junction. Variation in electrical conductivity of the nanowires with and without nanoparticles was highly dependent upon nanowire diameter for a constant nanowire length of 5μm. Bare GaN nanowire shows an exponential decrease in resistance (~ 450 KΩ to 1 KΩ) with increase in nanowire diameter (~ 50nm - 400nm). In case of Au-GaN nanowire, current-voltage measurements exhibited clear rectifying behavior, with the forward bias threshold voltage decreasing linearly with increasing nanowire diameter.