Photo-electrochemical gate recess etching for the fabrication of AlGaN/GaN heterostructure field effect transistor

This is the first report on wet gate recess etching for the fabrication of an Al0.2Ga0.8N/GaN heterojunction field effect transistors. Wet recess etching was performed using a photoresist etching mask without any additional dielectrics or metals. The rec etched surface was smooth and had no etch pits. After recess etching of a 300-Angstrom -thick n(+)-GaN cap layer, Schottky cor metals of Pt/Au were deposited on Al0.2Ga0.8N. Gate-to-drain breakdown voltage and gate leakage current at V-GD = 20 V were -80 V and -34 muA, respectively. The fabricated device exhibited a maximum drain current of 193 mA/mm and a maximum extrinsic transconductance of 62 mS/mm.