Nanocrystalline AlN:Si field emission arrays for vacuum electronics

Abstract

Nano-crystalline AIN : Si cold cathodes were grown by molecular beam epitaxy on prefabricated silicon μ-tip field emission arrays (FEAs). The investigated FEAs showed an uniform tip distribution and reproducible emission properties. Current densities of up to 0.7 mA for a 4 × 10 6 tips array (1 tip/μm 2) have been achieved at a relatively modest voltage of ∼ 60 V. The emitters revealed a good current stability with fluctuations of about 4% at constant voltage. The FEAs demonstrated a 40-fold decrease in operating voltage for a given current following the "activation" of the surface by high field conditioning. The corresponding changes in slope of the Fowler-Nordheim plot and UV photoemission spectra confirm that the surface cleaning causes a reduction of the surface emission barrier at least by factor of 3. The observed large electron affinity of the as loaded surface is presumed to be caused by the adsorption of oxygen and carbon containing species. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA.