Digital etching for highly reproducible low damage gate recessing on AlGaN/GaN HEMTs

A room temperature digital etching technique for aluminum gallium nitride has been developed. An oxidizing agent and an acid have been used in a two step etching cycle to remove aluminum gallium nitride in approximately 5-6 Å increments. The process has been characterized to be reasonably linear and highly repeatable, offering an alternative to currently not available gate recess etch stopper technologies. Recessed gate Al_0.35Ga_0.65N/GaN HEMTs on sapphire were compared to unrecessed devices realized on the same sample. A fivefold gate leakage decrease and negligible variations on breakdown voltage support digital recessing as a viable solution for highly reproducible low surface-damage gate recessed structures.