Effect of ultraviolet light on field emission performance and lifetime of lateral field emitter devices

Lateral field emission devices have been characterized before and after ultraviolet (UV) light exposure. Two types of planar device structures, diode and bowtie, were studied. These nanoscale devices have 9-15 nm tip-to-tip (bowtie) or tip-to-collector (diode) dimensions with the tips fabricated from Au/Ti. Typical currents of 2-5 nA per tip at 6 V were measured. It was observed that after UV exposure, the collected current was reduced by >28% for the case of a bowtie device; whereas the current was reduced by >39% for the case of a diode device. This reduction can be attributed to water vapor desorption on the dielectric surface between the structures, which in turn reduces surface leakage. The Fowler-Nordheim plot showed a straighter line after UV exposure. After the I-V test, the UV-exposed devices were placed on lifetime tests in a vacuum of <10(-8) Torr and were biased at 5 V DC. After 2600 h, an abrupt current decrease was observed: similar to 25% for the case of the bowtie and similar to 28% for the case of the diode device. Scanning electron microscope images of the bowtie and diode devices showed damage to the tips.