Ultrahigh-current field emission from sandwich-grown well-aligned uniform multi-walled carbon nanotube arrays with high adherence strength

We describe a new method to grow multi-walled carbon nanotube (MWCNT) arrays, which enable very high and stable macroscopic emission current density of 3.55 A cm(-2) along with a scalable total emission current of more than 710 mA. A sandwich-growth technology was employed to synthesize vertically well-aligned MWCNT arrays in large areas and patterned uniformly by using microwave plasma chemical vapour deposition. A thick nickel layer was inserted between the silicon substrate and catalyst layer to achieve good adhesion between the MWCNTs and the substrate. Scanning electron microscope and transmission electron microscope investigations showed that well-structured, vertically aligned and uniform MWCNTs with perfect crystal lattices had been grown on lithographically predetermined sites. The root ends of MWCNTs adhered firmly to the nickel layer, establishing high electrical and thermal conductance of the MWCNTs to the substrate. This feature largely explains the large and stable emission current density of the MWCNT arrays.