Comparison of damage introduced into GaN/AlGaN/GaN heterostructures using selective dry etch recipes

A SiCl₄/SF₆ dry etch plasma recipe is presented giving a selectivity of 14:1 between GaN and AlGaN. Using a leakage test structure, which enables bulk and surface leakage components to be identified independently, the optimized recipe is compared to an un-etched sample and devices recessed using a Cl₂/Ar/O₂-based plasma chemistry. Devices etched using the SiCl₄/SF₆ recipe demonstrated reduced bulk and surface leakage currents when operated over a wide range of temperatures. Consequently the SiCl₄/SF₆ recipe is identified as most suitable for the fabrication of gate recessed AlGaN/GaN HEMTs.