ELECTRON-EMISSION FROM A HYDROGENATED DIAMOND SURFACE

Electron emission from a polycrystalline diamond coated silicon field emitter surface was studied using in situ exposure to various gas spec ies during its operation. Significant enhancement of the electron emis sion was found after the emitting surface was exposed to hydrogen at p ressures in the range 5 X 10(-4) to 10(-3) Torr. Introducing other gas es such as Ne and He only suppressed the emission current. A continuou s emission current was measured from such a hydrogen-exposed surface e ven after the electric field was reduced to below the initial threshol d for electron emission, No similar result was found for pure silicon surface when identical conditions applied. This phenomenon was interpr eted as the formation of a dynamically vacuum-stable layer by polarize d hydrogen and the diamond surface. Such a surface layer may significa ntly lower the surface barrier and exhibit the negative electron affin ity property. (C) 1996 American Institute of Physics.