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

Abstract

We describe a new method to grow multi-walled carbon nanotube (MWCNT)arrays, which enable very high and stable macroscopic emission current density of3.55 A cm−2 along with a scalable total emission current of more than 710 mA. A sandwich-growthtechnology was employed to synthesize vertically well-aligned MWCNT arrays inlarge areas and patterned uniformly by using microwave plasma chemical vapourdeposition. A thick nickel layer was inserted between the silicon substrate andcatalyst layer to achieve good adhesion between the MWCNTs and the substrate.Scanning electron microscope and transmission electron microscope investigationsshowed that well-structured, vertically aligned and uniform MWCNTs with perfectcrystal lattices had been grown on lithographically predetermined sites. The rootends of MWCNTs adhered firmly to the nickel layer, establishing high electricaland thermal conductance of the MWCNTs to the substrate. This feature largelyexplains the large and stable emission current density of the MWCNT arrays.