AlN nanorod and nanoneedle arrays prepared by chloride assisted chemical vapor deposition for field emission applications

Hexagonal AlN nanorod and nanoneedle arrays were synthesized through the direct reaction of AlCl3 and NH3 by chemical vapor deposition at about 750 deg. C. Both the AlN nanoneedle and nanorod samples were of wurtzite structure and grew preferentially along the c-axis. With an increase in the ratio of NH3 to Ar, an evolution from nanorods to nanoneedles was observed. A growth model was proposed to explain the possible growth mechanism. Measurements in field emission show that AlN nanoneedle arrays have a much lower turn-on field (3.1 V μm-1) compared to nanorod arrays (15.3 V μm-1), due to their large curvature geometry. The AlN nanoneedle arrays have potential applications in many fields, such as electron-emitting nanodevices and field-emission-based flat-panel displays