High Power AlGaN/InGaN/AlGaN/GaN Recessed Gate Heterostructure Field Effect Transistor with InGaN as the RIE Etching Stop Layer

We propose to a new approach AlGaN/GaN Heterostructure Field Effect Transistors (HFET) technology for reliable, stable, high-power microwave amplifiers using novel recessed gate/active passivation design. Under certain process conditions of BCl3 RIEetching for optimized InGaN films, the In etch product InCl3 will be formed on the surface stopping any further etching. The RIE etching rate of InGaN is much lower than the etching rate of AlGaN or GaN layers. Hence, InGaN can serve as RIE etch stoplayers. The thin InGaN film can be wet chemically etched by diluted KOH. The etching rate and etching pattern can be well controlled. The BCB passivation or Si3N4 passivation will be used to prevent AlGaN oxidation. Our approach will be used to improvethe breakdown voltage and output power for microwave power amplifiers, which is a key for the Transmit/Receive (T/R) module.