Field Emission Properties of Top–Down GaN Nanowires Characterized in Vacuum by a Nanometer-Resolution Piezoelectric Probing System

Gallium nitride (GaN) nanowire (NW) vacuum field emission (FE) devices are promising candidates for next generation devices, as they are expected to combine the advantageous features of solid-state devices with those of vacuum electronics. The performance of these devices relies on NW formation with well-defined cylindrical shape and minimum surface damage, while their accurate evaluation requires nanometer-resolution probing. To address the latter, top–down GaN NW FE devices with an integrated leveling structure were fabricated and their characteristics are reported. A custom-made vacuum characterization system with a 1-mm-diameter cylindrical piezoelectrically actuated probe with nanometer-resolution, served as the anode of the FE device, in the characterization system used for studying the GaN NW FE devices. The fabricated FE devices exhibited a maximum current density of ~ 1.0 A/cm² and a turn-on voltage of ~ 85 V, using a total number of 22,500 NWs with 160 nm diameter and a ~ 2-μm anode to NW separation distance. Further improvement of the technology could enable the exploitation of the piezoelectric system for probing with nanometer-scale vertical resolution FE devices with closely spaced anode to cathode configurations. This characterization system and the proposed process flow can also be adopted for the nanometer-resolution piezoelectric probing of different semiconductor NW materials, providing an easy and cost-effective way of FE measurements of vertical NWs.