Phosphorus doped polycrystalline diamond films were grown using ion implantation in various process steps and were structurally and electrically characterized. When the diamond alms were implanted after pretreatment or in the course of diamond growth and were grown by microwave plasma chemical vapor deposition, some modified structural characteristics and improved electrical characteristics were obtained. Secondary ion mass spectrometry analyses of some diamond films led to the conclusion that phosphorus ions and defects in the Si-diamond interface play an important role in the enhancement of field emission from diamond films. (C) 2003 American Vacuum Society.