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 Al_0.2Ga_0.8N/GaN heterojunction field effect transistors. Wet recess etching was performed using a photoresist etching mask without any additional dielectrics or metals. The recessetched surface was smooth and had no etch pits. After recess etching of a 300-Å-thick n⁺-GaN cap layer, Schottky contact metals of Pt/Au were deposited on Al_0.2Ga_0.8N. Gate-to-drain breakdown voltage and gate leakage current at V_GD = -20 V were -80 V and -34 μA, respectively. The fabricated device exhibited a maximum drain current of 193 mA/mm and a maximum extrinsic transconductance of 62 mS/mm.