Effect of Ultra Violet Light on Planar Field Emitters

Two different types of planar nano-scale (4–5 nm) field emitters, bowtie and diode devices, were characterized for use as electron sources for vacuum nano-transistors. I-V measurements were performed before and after Ultra-violet (UV) light exposure. Experiments showed that the field emission current was $\approx 2.7 \text{nA}$ before the UV exposure and was $\approx 1.8\text{nA}$ after the exposure for the bow-die devices. Experiments also showed that the field emission current was $\approx 5.6\text{nA}$ before the UV exposure and was $\approx 3.6 \text{nA}$ after the exposure for the diode devices. This reduction in current could be attributed to the removal of water vapor by UV exposure resulting in the reduction in the surface leakage current. A long-term stability tests conducted after the UV exposure showed both the bow-tie and diode devices emitted a stable current (<5% drop) for > 1100 hrs. of continuous operation at a DC bias of 5 V.