Performance improvement of gated silicon field emitters with a thin layer of boron nitride

Fully processed boron implanted n(-)-gated silicon tip arrays were coated w ith about 50 nm of carbon-doped BN by reactive sputtering at 450 degreesC. The current-voltage characteristics of the BN coated 6460 tip arrays shifte d by about 40-60 V towards lower gate voltages for emission currents of abo ut 100 muA. From the Fowler-Nordheim analysis of representative arrays, the alpha (3/2)/beta ratio decreased from 2.5x10(-5) eV(3/2)cm to 8.9x10(-6) e V(3/2)cm for the coated tips. This decrease is attributed to an increase in the field conversion factor beta. The arrays improve in performance when o perated at 40 mA/cm(2) for about 100 h in direct current mode and show a fa ctor of 6 increased pressure tolerance towards ion bombardment as compared to the bare silicon emitters. (C) 2001 American Vacuum Society.