Field emission characteristics of diamond nano-tip array fabricated by anodic aluminum oxide template with nano-conical holes

Abstract

Different sizes and periods of diamond nano-tip arrays are fabricated by anodic aluminum oxide (AAO) template with nano-conical holes. Before the anodic oxidation process, 99.5% Al sheets are annealed and electro-polished. AAO templates with nano-conical holes are obtained by continuously changing voltages from 40 to 160V in 0.3M oxalic acid at the temperature of −3°C. The aluminum pore of AAO is then removed by the wet etching solution of CuCl and HCl. Diamond nano-particles of diameters of 4–12nm are adhered to the AAO template as the nucleation sites by Polyethylenimine method. The diamond nano-tip arrays are deposited on the template by microwave plasma chemical vapor deposition with the mixture gas of methane and argon. The diamond nano-tip array of different sizes and periods are obtained after the AAO template is completely removed by NaOH etching. The ratio of nano-tip spacing to the pitch-height (pitch-height ratio) ranges from 1 to about 2.5. The diamond nano-tip array with the smallest spacing-height ratio of 1 by the AAO template with nano-conical holes has the highest field enhancement factor (β) of 4885 and the lowest turn-on field of about 2.63V/μm.