The effect of nanoscale protrusions on field-emission properties for GaN nanowires

GaN nanowires (NWs) have been synthesized on platinum-coated silicon (111) substrates by the chemical vapor deposition (CVD) method under different NH3/H-2 carrier gas-flow rate ratios. X-ray diffractometer and transmission electron microscope analyses indicate that GaN NWs have wurtzite structures. Nanoscale protrusions with crystal orientation along the (002) direction were observed on the surface of GaN NWs grown under high H-2 flow rate conditions. As compared to the field-emission result of GaN NWs with smooth surfaces, GaN NWs with nanoscale protrusions exhibit a lower turn-on field of 8.5 V/mu m and a higher field-enhancement factor of beta=315. These nanoscale protrusions are believed to account for the enhancement of the field-emission behaviors of GaN NWs. (c) 2007 The Electrochemical Society.