Synthesis and field emission of high pure AlN nanowires

Ever since Spindt field emitter arrays were invented, great efforts have been devoted to explore novel electron sources for better and more reliable performance. In addition to carbon series (diamond films, diamond-like carbon films, carbon nanotubes, and etc.), the one-dimensional (1D) nanostructures of group III nitrides, GaN, AlN, InN and their alloys, are expected to be a kind of promising candidates due to the combination of 1D geometries, small or even negative electron affinity (NEA) and adjustable bandgap which is beneficial for field emission. Our recent study did indicate the good field emission properties of AlN nanowires prepared by the extended vapor-liquid-solid growth (Wu et al., 2003). Herein we report a improved method to fabricate pure AlN nanowires. The white AlN nanowires were produced by the reaction of Al powder and carbon-coated Ni nanoparticles at 1400/spl deg/C and collected from the down-stream of the reaction tube. The products were well characterized by TEM, SEM, XRD and Raman spectrum. The field emission properties of AlN nanowires were measured in a vacuum chamber at a base pressure of /spl sim/1/spl times/10/sup -7/ Torr. The emission current-voltage (I-V) curve were repeatedly measured by a Keithley system for different distances (D) between the sample and anode. The I-V curve qualitatively follow the conventional Fowler-Nordheim behavior according to the straight line plot of log (J/E/sup 2/) versus I/E. The field emission mechanism is also discussed.