Long Term Field Emission Current Stability Characterization of Planar Field Emitter Devices

Lateral field emission devices have been characterized and degradation tested for >1000 h to study stability and reliability. Two types of planar device structures, diode and bowtie, were studied. These nanoscale devices have 10-20 nm tip to tip or tip to collector dimensions with the tips fabricated from Au/Ti. Typical currents of 2-6 nA at 6 V were measured. The devices were placed on lifetime tests in a vacuum of <10⁻⁸ Torr and biased at 6 V DC for >1000 h. Seven total devices were tested with one failing at 300 h. and three of the devices showed <5% degradation in current until 1400 h when testing was stopped, and three other devices showed a sudden drop of ≈20% ranging from 700 to 900 h. Optical microscope images of one of the devices that failed catastrophically at 350 h show physical arc damage where the bond pad narrows to the emitter trace. Scanning electron microscope images of a bowtie part that completed 1400 h of operation showed no obvious erosion or damage to the tips.