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 H2 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 H2 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 Vμm and a higher field-enhancement factor of Β=315. These nanoscale protrusions are believed to account for the enhancement of the field-emission behaviors of GaN NWs.