Patterned growth and field emission properties of vertically aligned carbon nanotubes

摘要

Vertically aligned carbon anotubes were grown selectively on patterned Ni thin films by microwave plasma-enhanced chemical vapor deposition andtheir field emission properties were investigated using a diode-structure.Ni thin films patterned with a form of dot-arrays were prepared using a shadow mask having an array of holes.The nanotubes were found to be well-graphitized with mutiwalled structures.The measurements of field emission properties revealed that the carbon nanotube tips emitted high current density at low macroscopic electric field.The Fowler-Nordheim(F-N) plot clearly showed two characteristic regions where the current saturates at the high electric field region.It was found that the saturation behavior was caused by the adsorbates-enhanced field emission mechanism.Eliminating the adsorbates resulted in no saturation behavior,increasing turn-on field,decreasing current,and increasing field enhancement factor.Using ZnS/Cu,Al phosphor,very bright and uniform emission patterns were obtained.