Epitaxially grown GaN nanowire networks

GaN nanowires grown by means of the chemical vapor deposition (CVD) method on a catalyst-deposited substrate are typically known to exhibit a vertical growth pattern and crystallize in the hexagonal wurtzite structure. Here, we demonstrate CVD grown GaN nanowires on Ni-catalyst deposited sapphire substrates where the nanowires exhibit a horizontally aligned, epitaxial growth pattern. The nanowires are in the form of organized networks with hexagonal symmetry which coincides with the surface structure of the sapphire substrate. This growth pattern is achieved through the use of a controlled catalyst deposition method which produces Ni catalyst nanoparticles with small diameter, less than 50nm. Photoluminescence measurements indicate a possible cubic zinc blende type crystal structure. Transport measurements indicate excellent current-carrying capacity for such epitaxial GaN nanowires with potential applications in advanced nanoelectronic devices as demonstrated here by a top-gate nanowire FET. The large area scalability of the network growth pattern and easy compatibility with device-fabrication processes make such epitaxial GaN nanowire networks potentially significant for advanced nanoscale devices.