Field emission study of gated GaN and Al0.1Ga0.9N/GaN pyramidal field emitter arrays

A self-aligned process has been proposed for fabrications of gated GaN and Al0.1Ga0.9N/GaN pyramidal field emitters with a small and precise distance between the gate electrode and the emitter tip. The sharp pyramidal emitters were obtained by a selective area growth technique. SiO2 and polyimide were used as the insulating layers between the emitters and the gate electrode. The gate-tip spacing and the tip protrusion through the gate openings were precisely controlled by adjusting the thickness of the SiO2 and polyimide layers. The turn-on voltage was reduced by narrowing the gate-tip spacing and by using Al0.1Ga0.9N/GaN emitter instead of GaN; the low onset gate voltage of 42 V was obtained for a gate-tip spacing of 0.4 μm.