Field emission properties of nitrogen-doped diamond films

This study explores the field emission properties of nitrogen-doped diamond grown by microwave plasma chemical vapor deposition. Over 70 nitrogen-dope d diamond samples were grown on silicon and molybdenum under varying proces s conditions. Under certain conditions, films can be grown which exhibit ph otoluminescence bands at 1.945 and 2.154 eV that are attributed to single s ubstitutional nitrogen. Photoelectron emission microscopy with UV free elec tron laser excitation indicated a 0 or negative electron affinity. Field em ission characteristics were measured in an ultrahigh vacuum with a variable distance anode technique. For samples grown with gas phase [N]/[C] ratios less than 10, damage from microarcs occurred during the field emission meas urements. Samples grown at higher [N]/[C] content could be measured prior t o an arcing event. Contrary to other reports on nitrogen-doped diamond, the se measurements indicate relatively high threshold fields (> 100 V/mu m) fo r electron emission. We suggest that the nitrogen in these films is compens ated by defects. A defect-enhanced electron emission model from these films is discussed. (C) 1999 American Institute of Physics. [S0021-8979(99)05719 -9].