Controllable low temperature vapor-solid growth and hexagonal disk enhanced field emission property of ZnO nanorod arrays and hexagonal nanodisk networks

ZnO nanorod arrays and nanodisk networks were grown directly on Si substrate by thermal evaporation of ZnCl ₂ powder and a mixture of ZnCl ₂ and InCl ₃̇4H ₂O at 450 °C in air, respectively. The ZnO nanorods with the diameters of 0.64 to 0.91 μm and length of about 5.1 μm are single crystalline with the hexagonal structure and grow along the [001] direction. The nanodisk has perfect hexagonal shape, grow mainly along the 〈011̂0〉 directions, and are enclosed by ±(0001) top and bottom surfaces. ZnO nanoparticle films oriented in the [001] direction formed first served as seeds, and grow into nanorod arrays via the vapor-solid (VS) process. However, when InCl ₃̇4H ₂O was introduced into the reaction system ZnO thick nanosheet films are first formed because of the local segregation of the doping element of indium. The ZnO thick nanosheet films served as seeds, and grow into nanodisk networks via the V-S process. Photoluminescence and field emission properties of the as-obtained ZnO nanorod arrays and hexagonal nanodisk networks have been studied. It was found that the hexagonal nanodisk networks exhibit strong blue-green emissions originated from defect states and enhanced field emission property.