THE EFFECT OF HYDROGEN AND ACETYLENE PROCESSING ON MICROFABRICATED FIELD EMITTER ARRAYS

Molybdenum tips of the ''Spindt'' type field emitter arrays have been subjected to processing in hydrogen and acetylene gases. The current-voltage characteristics gave linear Fowler-Nordheim plots. Work function changes for the different processes were estimated from these plots. Processing in a hydrogen plasma leads to a lower work function, decreasing by 0.92 eV after 100 min of treatment. The emission current for a given applied voltage increases substantially immediately after hydrogen treatment but slowly declines to its original untreated value after 30-100 hours. The process can then be repeated indicating that the effect is due to reversible changes in the surfaces such as may be caused by adsorption phenomena rather than changes in the geometry or emitting area of the tips. Drawing emission current in an acetylene atmosphere (approximately 10(-5) Torr) produces a permanent decrease in the work function by up to 1.1 eV, presumably as a result of carbon deposition on the tips. Repetitive processing showed further but smaller work function decreases. The emission at a given voltage is further improved slightly by heating to 285-degrees-C and is accompanied by changes in the emission parameters estimated from the FN plots.