Field emission characterisation of silicon tip arrays coated with GaN and diamond nanoparticle cluster

Wide band gap materials show promise for applications in coating of field emission tips. Recently nanocrystalline hexagonal GaN crystallites as small as 5 nm average diameter have been formed using reactive laser ablation of gallium metal in a nitrogenating ambient. In this paper we have investigated the performance of ungated emitter. Silicon tip arrays coated by dielectrophoresis of gallium nitride nanoparticles or nanocrystalline diamond clusters from an ethanol suspension. The emitters were evaluated and compared before and after the surface treatment using SEM images and I-V measurements in the diode configuration. The phosphor screen, used as the anode was spaced nominally 70 μm from the cathode. A field emission characteristics were measured in a high-vacuum chamber at a pressure range between 10 ^-5 and 10^-8 Torr. The results suggest that the emitters benefit from coating the surface with nanocrystalline diamond clusters in terms of reduction in the turn on voltage and increase in the uniformity of emission in low voltage operation. The long-term emission stability was studied over a period of 90 hrs