Influence of Dry Recess Process on Enhancement-Mode GaN Metal–Oxide–Semiconductor Field-Effect Transistors

Abstract

To gain a flat recess profile with uniform etching depth, dry recess experiment with different inductively coupled plasma (ICP) etching conditions was done on an AlGaN/GaN heterostructure. Trenching effect at the bottom near the sidewall was observed when positive photoresist was utilized and the ICP power was low. The recess profile was improved by adopting SiO 2 as the etching mask and increasing the ICP power. GaN metal–oxide–semiconductor field-effect transistors (MOSFETs) on AlGaN/GaN heterostructure with different gate recess conditions were fabricated and characterized. The maximum field-effect mobility of 152.8 cm -2 V -1 s -1 and the minimum interface state density of 1.39×10 11 cm -2 eV -1 were obtained from the optimized gate recess condition with ICP power of 100 W, bias power of 20 W and etching mask of SiO 2 .