The effect of nitrogen addition to Ar/CH4 plasmas on the growth, morphology and field emission of ultrananocrystalline diamond

Abstract The effect of the addition of nitrogen to plasmas during the CVD growth of diamond films on field emission properties has been studied. Ultrananocrystalline diamond with 5–15 nm grain size has been grown with the incorporation of nitrogen up to 8×1020 atoms/cm3. Field emission onsets as low as 2 V/μm have been achieved. UV Raman and electron energy loss spectroscopy (EELS) measurements show an increase in the sp2 content in the films with nitrogen in the plasma compared to films without N2 addition. A model is discussed in which the nitrogen preferentially enters the grain boundaries and promotes sp2 bonding in the neighboring carbon atoms. The increase in the sp2 content appears to improve the field emission properties of the films.