Long-term stability of various carbon-nanotube-based micro-tip emitters

The electron emission property and long-term stability of the emission current in various field emitters based on carbon nanotubes (CNTs) with a CNT/catalyst/buffer/W-tip configuration were examined. CNT-based field emitters were fabricated by varying the buffer layers (TiN, Al/Ni/TiN) and the catalyst materials (Ni, Co). The crystalline structure, surface morphologies, and nanostructures of all the grown CNTs were analyzed using Raman spectroscopy, field emission SEM, and high-resolution TEM. X-ray photoelectron spectroscopy (XPS) was used to monitor the chemical bonds of all the buffer and catalyst layers. When measured, the field emission characteristics showed the emitter that used the Al/Ni/TiN stacked buffer and the Co catalyst exhibited the best performance: a maximum emission current of 51 μA, a threshold field of 2.52 V/μm, and no degradation of emission current after a prolonged (up to 40 h) operation.