Photo-electrochemical gate recess etching for the fabrication of AlGaN/GaNheterostructure 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 etch ing was performed using a photoresist etching mask without any additional d ielectrics or metals. The rec etched surface was smooth and had no etch pit s. After recess etching of a 300-Angstrom -thick n(+)-GaN cap layer, Schott ky cor metals of Pt/Au were deposited on Al0.2Ga0.8N. Gate-to-drain breakdo wn 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 19 3 mA/mm and a maximum extrinsic transconductance of 62 mS/mm.