Field emission from nanodiamond grown with ‘ridge’ type geometrically enhanced features

Cold cathodes for vacuum field emission have many interesting applications including display devices. Chemical vapor deposited (CVD) diamond has long been considered such a candidate. A nanodiamond film with ridge features was grown on a highly doped (resistivity = 0.0035 Ω-cm) n-type silicon substrate by plasma enhanced CVD process using a H2/CH4/N2 gas mixture. The overall planar nanodiamond film was characterized for vacuum field emission in diode configuration. A low turn on field of ~ 2.3 V/µm at 1 µA was observed. The cathode was able to produce 150 µA at a field of 6.6 V/µm. This field emission behavior can be attributed to a combination of high sp2 content, higher electrical conductivity by nitrogen incorporation in the nanodiamond film and a high geometrical field enhancement factor because of the sharp ‘ridge’ like features on the surface.