Effect of boron/nitrogen co-doping on the electron field emission characteristics of nanocrystalline diamond films was examined. The,diamond grains, which are of faceted geometry and about 0.5-1 mum in size, vary insignificantly due to incorporation of boron and nitrogen species. Raman spectroscopies also do not change with the doping concentration. However, B/N codoping markedly improves the electron field emission properties of the diamond films. The electron field emission current density increases from (J(e))(B1)=20 muA/cm(2) for diamond films containing 1 sccm B(OCH3)(7), to (J(e))(B3) = 250 muA/cm(2) for those containing 3 sccm B(OCH3)(3). The electron field emission capacity further increases to (J(e))(B3N3) = 1750 muA/cm(2) for diamond films co-doped with 3 sccm B(OCH3)(3) and 3 sccm (NH3)(2)CO. Atomic force microscopies reveal that the electronic structure. of diamonds was markedly modified due to boron/nitrogen co-doping. (C) 2003 American Vacuum Society.