Nano-scale diamond tips: Synthesis in the CH4/N2/H2 plasma

We report the discovery of vertically aligned nano-scale diamond tips grown on the polycrystalline diamond substrates in a CH4/N2/H2 mixed plasma. The best diamond quality occurs at the top part of the nanotip, which is single crystalline diamond. The quality of the diamond nanotip is justified by the diamond characteristic peak at 1332 cm− 1 in the Raman spectrum, the discrete electron diffraction pattern of diamond along [011] zone axis, and the electron energy loss spectra. Single crystalline diamond with poor quality appears at the center and the bottom part of the nanotip. No nitrogen K edge signal appears in the electron energy loss spectra, suggesting that nitrogen is very difficult to incorporate into the diamond nanotip. The roles of nitrogen in the formation of diamond nanotips are discussed.