Synthesis and electron emission properties of aluminum nitride nano-cones

Aluminum nitride nanowires have displayed superior field emission due to the combination of negative electron affinity and one-dimensional geometry (Wu et al., 2003). Here we report on the preparation and field emission properties of quasi-aligned aluminum nitride nano-cones on the silicon wafer. These nano-cones are formed via the reaction between AlCl₃ vapor and NH₃/N₂ gas at the temperature ranging from 700°C to 800°C under nickel catalyst. The subsequent analyses including X-ray diffraction, scanning electron microscopy and transmission electron microscopy indicate that these cones have wurtzite phase and grow preferentially along c-axis with the linear decreasing diameter. The diameters of the tips of these cones are measured to be between 20 and 50nm. Field emission measurements were carried out in the vacuum chamber at the pressure of 1×10_-7 Torr at the ambient temperature. From the characteristic current-voltage curves, it is revealed that the turn-on voltage is about 12V/μm comparable with that of GaN nanowires. Based on the Fowler-Nordheim plot with two-stage slope, the field enhancement factors are calculated to be about 400 and 1200 respectively. These results indicate that these AlN nano-cone arrays may have promising application in field of electron emission emitters.