Surface damage on diamond-based electron emitters

To determine the optimum conditions for eliminating surface damage, formation mechanisms of surface damage on diamond-based emitters were investigated for undoped and B-doped diamond films and diamond-like-carbon films grown by microwave-plasma chemical vapor deposition. Surface damage with craters was observed for films of various thicknesses upon applying an anode voltage of less than 2000 V. Formation of damage was controlled by the electric field in the gap between the diamond surface and the anode. The minimum electric field which did not damage the surface was determined to be around 80 V/mum. The electric field in the diamond films was insensitive to the formation of the surface damage. This indicated that dielectric breakdown of the diamond films was not the primary cause of surface damage.