Cold cathode structures have been fabricated using AlN and graded AlGaN structures (deposited onn-type 6H-SiC) as the thin film emitting layer. The cathodes consist of an aluminum grid layer separated from the nitride layer by aSiO2layer and etched to form arrays of either 1, 3, or 5 &mgr;m holes through which the emitting nitride surface is exposed. After fabrication, a hydrogen plasma exposure was employed to activate the cathodes. Cathode devices with 5 &mgr;m holes displayed emission for up to 30 min before failing. Maximum emission currents ranged from 10–100 nA and required grid voltages ranging from 20–110 V. The grid currents were typically 1 to104times the collector currents. ©1997 American Institute of Physics.