Synthesis and field emission characteristics of carbon nanocoils with a high aspect ratio supported by copper micro-tips

Carbon nanocoils (CNCs) were synthesized via thermal chemical vapour deposition (CVD) with C₂H₂ and NH₃ gases at 600°C. A Ni catalyst was placed upon the copper micro-tip structures that were fabricated on a silicon substrate. Our CNCs had a long rope shape with a length not exceeding 100 μm and a nanoscale diameter. The copper micro-tips were formed through high current pulse electroplating, which played a significant role in characterizing our CNCs. The CNCs grown on the copper micro-tips showed outstanding field emission performance and long-term stability. Their turn-on field, defined as that at a current density of 10 μA cm^-2, was 1.30 V μm^-1 and the maximum current density reached 11.17 mA cm^-2 at an electric field of 2.39 V μm ^-1.