Large-Signal Performance Comparison of Ion Implant and Mesa Etch Isolated AlGaN/GaN HEMT Switches on Silicon

This study presents a comparative analysis of large-signal performance for AlGaN/GaN high electron mobility transistor (HEMT) switches on a silicon substrate, isolated using either ion implantation or mesa etching. The investigation focuses on the impact of isolation methods on gate leakage, RF isolation, and harmonic distortion. While DC-IV measurements indicate significantly higher gate leakage in mesa etch isolated devices, small-signal S-parameter measurements indicate that both isolation methods provide effective <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{R F}$</tex> isolation. Large-signal measurements demonstrate that ion implantation isolated devices exhibit greater non-linearity and harmonic distortion compared to mesa etch isolated devices. For the largest device type, the mesa etch isolated switch had a 37% higher 1 dB compression point. Higher harmonic distortion for ion implantation isolation was attributed to reduced effective substrate resistivity.