Temperature Dependence of the Field Emission Characteristics of AlGaN/GaN Nanoscale Vacuum Diodes

We investigate the temperature dependence of field emission (FE) characteristics of AlGaN/GaN heterojunction-based lateral nanoscale vacuum diodes over a temperature range varying from 77 to 373 kelvin. The vacuum diodes have a sharp (trochoidal-like) cathode and blunted anode with the shortest distance between the tip of the cathode and the anode of 210 nanometers. The DC FE characteristics were recorded using a compliance current of 100 nanoamperes. Under forward mode of operation, the vacuum diodes exhibit three regimes of operation: one associated with FE from adsorbates on the tip of the cathode at low applied bias, followed by FE from the bare cathode at larger forward bias, and finally onset of self-heating effects. The latter leads to a smaller FE current under reverse sweep. In the reverse sweep, the current-voltage characteristics suggest the onset of conduction through the substrate.