Field emission properties of diamond films were studied by macroscopicI–Vmeasurement. A lower turn-on field and a higher emission current were observed for diamond films produced by higher methane concentration, or with higher density of defects, introduced by ion implantation. However, diamond films of poorer quality experience a severe reliability problem. Cold implantation followed by rapid thermal or laser annealing produced diamond emitters with a turn-on field as low as 5 V/&mgr;m and the desired reliability. ©1997 American Institute of Physics.