Field emission characteristics of AlGaN/GaN nanoscale lateral vacuum diodes

Abstract

We report the design, fabrication, and measurement of the field emission (FE) characteristics of AlGaN/GaN nanoscale lateral vacuum diodes with triangular cathodes and cathode to anode spacings from 50 to 600 nm. The FE characteristics of the AlGaN/GaN diodes with metallic or AlGaN/GaN anodes show successful rectification with forward bias FE current in the range of microamperes or milliamperes, respectively, when biased within a maximum range varying from 10 to 30 V. In the forward bias mode, the measured current Im vs applied anode to cathode bias Vm are well fitted to Murphy–Good profiles associated with FE at higher biases, and an Ohmic leakage profile below the threshold for FE. Our results are the first successful demonstration of FE of electrons between the two two-dimensional electron gases (2DEGs) present on both sides of a nanogap formed by electron lithography through an AlGaN/GaN heterojunction. A qualitative explanation of the loop-type FE characteristics of both AlGaN/GaN vacuum diodes, with either metallic or AlGaN/GaN anodes, is presented.