InGaN-Channel Heterostructure Field Effect Transistor With Double Recessed Gate for Improved RF Performance

Sensor Electronic Technology Inc. proposes to develop a new epitaxial layer design with ternary (InGaN) and quaternary (AlInGaN) stop etch layers for double recess device fabrication. We already demonstrated significant improvement in the RF performance of AlGaN/InGaN/AlGaN/GaN-based HFETs with the recessed gate design. We used our novel Migration Enhanced MOCVD (MEMOCVDTM) deposition technique to incorporate a very thin (2 nm) InGaN layer into the AlGaN barrier. The InGaN layer was used as a stop-etch layer for RIE etching and selective wet chemical etching was used to remove the InGaN stop-etch layer using two proprietary etch processes. We propose to combine this approach with our novel AlGaN/AlInGaN/InGaN/GaN based Triple HFET (THFET) design. A quaternary AlInGaN cap layer grown over the InGaN channel will be used as a second stop etch layer for the RIE. We will recess both source and drain contacts and will fabricate them on the In-containing AlInGaN cap layer for reduced contact resistance. The expected benefits of the proposed design are higher gain and breakdown voltage, better linearity of the RF devices and suppression of current dispersion. We will also use our MOSHFET gate dielectric process to achieve superior device reliability and stability for transition to commercialization.