Fabrication of recessed-gate AlGaN/GaN MOSFETs using TMAH wet etching with Cu ion implantation

Abstract

In this study, recessed-gate AlGaN/GaN MOSFETs were fabricated using a novel recess etching method––TMAH wet etching with Cu ion implantation. This innovative approach injects Cu ions selectively into the target AlGaN layer, creating defects that are then etched with a TMAH solution, dissolving Ga along with the defect. Compared to the conventional GaN recess etching method of ICP-RIE dry etching, TMAH wet etching offers more precise etching without causing plasma damage on the etched surface. To demonstrate the superiority of TMAH wet etching, devices fabricated with this method were analyzed and compared with devices fabricated using ICP-RIE dry etching. The AFM images of the etched surface demonstrated the superior stability of TMAH wet etching. In addition, electrical characteristics measurements revealed that the devices using TMAH wet etching exhibited a higher on-current (295.05 mA/mm), lower gate lag rate (15.98 %), and a higher breakdown voltage (733 V) than ICP-RIE etched devices.