InGaP/GaAs DHBTs with composite collectors for power amplifiers

InGaP/GaAs double heterojunction bipolar transistors (DHBTs) with composite collectors have been proposed, simulated and fabricated for power amplifier applications in wireless communication. The composite collector combines wide-bandgap (InGaP) and narrow-bandgap (GaAs) materials. InGaP provides a high breakdown field and thus can be employed to reduce collector thickness while maintaining breakdown voltage. GaAs provides high electron mobility and thus is able to be used to reduce on-resistance and transit time. Three InGaP/GaAs HBTs with different collector structures have been grown, fabricated and characterized. The Gummel plots from simulation and measurement for the proposed DHBT show negligible difference in current gains, which is due to the identical structures in base/emitter regions and effectively reduced conduction spike in the base-collector junction. Overall, this DHBT with displays improved performance in on-resistance and knee voltage.