The effect of Cu ion implantation and post-annealing on surface morphology and electron field emission in ultrananocrystalline diamond

The effects of 100 keV Cu ion implantation and subsequent annealing (i.e. common annealing or rapid annealing) at 500 °C on modifying the surface morphology and the electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films were investigated. A Common annealing provides moderate enhancement in both electrical and EFE properties. Besides, the rapid annealing results in a low surface resistivity of 10.3 Ω/sq with a high mobility of 346.5 cm2 V−1 S−1for the UNCD film. The corresponding EFE behavior can be turned on at E0 = 5.3 V/μm, attaining a current density of 426.7 μA/cm2 at an applied field of 8.1 V/μm. The Mesh-like surface structures with the plate-like particulates, approximately 20-30 nm in size, distributed on the sample surface, which implies that the melting and recrystallization process have occurred due to the rapid annealing. Raman and X-ray photoelectron microscopy results demonstrated that the formation of Cu nanoparticles in UNCD films could catalytically provoke the formation of abundant nanographitic phase during rapid annealing process, forming the conduction channels for electron transport. Finally, the conducting and EFE properties of the UNCD films were remarkably improved.