ICP-CVD SiN Passivation for High-Power RF InAlGaN/GaN/SiC HEMT

High-frequency Metal Insulator Semiconductor High-Electron-Mobility Transistors (MIS HEMTs) were fabricated on quaternary InAlGaN/AlN/GaN heterostructures, grown by MOCVD on a 3” SiC substrate. Specific studies were performed on SiN ICP-CVD passivation layers. Improved performances were obtained with these optimized devices at 30 GHz as evidenced by CW Load Pull characterization: an output power of 6 W/mm and a power-added efficiency of 42%. A good extrinsic transconductance value higher than 450 mS/mm and a current density up to 1.55 A/mm were also measured on these transistors.