Copper nanowire–carbon nanotube hierarchical structure for enhanced field emission

Field emitters have found ample variety of applications from field emission displays to high power microwave generators. Though a myriad of materials have been considered for emitter application, carbon nanotubes (CNT) are prominent to offer outstanding field emission characteristics, owing to its nano-dimensions and excellent electrical transport properties. While nano-apex of CNTs aids in achieving high field enhancement factor, its high electrical conductivity ensures minimum resistance to electron flow. Next-generation field emitters demand to show high emission current, at a lower applied electric field, which can be achieved by a three-dimensional (3-D) emitter structure. In this research work, a 3-D hierarchical field emitter structure was synthesized involving carbon nanotubes (CNT) on copper nanowires (Cu NW). Field emission characterization of this hierarchical structure in DC bias showed a low turn-on field of 1.8–2.1 V/µm and maximum current density of 1.84 mA/cm2. CuNW–CNT emitter also demonstrated a remarkable emission stability of nearly 8 h which is very significant for practical applications. Properties of the field emitter CuNW–CNT hierarchical emitter was correlated with its morphology.