Mt. Mcclure et al., ELECTRICAL CHARACTERIZATION OF DIAMOND AND GRAPHITE COATED MO FIELD EMITTERS, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 15(6), 1997, pp. 2067-2071
Current-voltage characteristics of tip-shaped molybdenum field emitter
s were investigated before and after coating with diamond or graphite
powders. Stable emission was observed only after annealing and formati
on of a conductive Mo carbide layer at the metal-coating interface. Bo
th coated emitters displayed enhanced emission and ''turn-on'' voltage
s reduced by a factor of 2 as compared to the uncoated emitters. For t
he graphite coated emitter, the enhancement was attributed to an incre
ase in the field enhancement factor due to the coating morphology. Rou
ghening of the Mo-diamond interface via carbide formation during the a
nnealing step was presumed to have been the cause for the enhanced emi
ssion for the diamond coated emitter. The transmission probabilities f
or the Mo-diamond and diamond-vacuum interfaces were calculated, using
the WKB method, based on an emission mechanism from the intrinsic dia
mond's conduction band minimum. With a field locally enhanced to 10(8)
V/cm, the transmission probability for the diamond-vacuum interface w
as 10(8) times larger than that of the Mo-diamond interface. This eval
uation confirmed that the electron affinity of the diamond surface is
not a governing factor in the emission from intrinsic diamond. (C) 199
7 American Vacuum Society.