Arrays of carbon nanoflake spherules realised on copper substrate

Arrays of carbon nanoflake spherules (CNSs) have been grown on the copper substrate by the microwave plasma assisted chemical vapour deposition method. Uniform sized CNSs of diameters of 700–950 nm have been produced. The CNSs are free from any other carbon nano-structures. The growth of CNSs has been found to be strongly affected by the undulating surface (crest–trough morphology) of the substrate with preferential growth along the direction of crests. Micro-Raman spectroscopic analysis reveals highly active surface of the graphitic edges of as-grown CNSs. A possible growth mechanism has been proposed which could be used for a large yield of arrays of the CNSs. The field-emission measurements show potential applications of the CNSs in the vacuum electronics devices with a low turn-on field of 7.4 V/μm.