Improvement In AlGaAs/GaAs HBT power gains with buried proton-implanted layer

A new structure for AlGaAs/GaAs heterojunction bipolar transistors (HBTs) that employs a buried proton-implanted external collector layer is proposed. This structure has been successfully used to achieve high-performance HBTs with maximum oscillation frequencies fmax up to 51 GHz for a device with 2 ?×5 ?m emitter and 4 ?m×7 ?m collector dimensions.