Optimization of the collector profile of InGaP/GaAs HBTs for increased robustness

Heterojunction bipolar transistors are often used for power amplifiers, e.g. in GSM phones. Such applications require very robust devices that are able to withstand large voltages and currents. For this, an adequately chosen collector doping profile is a key parameter. In this work, we present a technique for optimizing the collector doping profile with respect to transistor robustness. The applicability of our approach is demonstrated experimentally by measurements of InGaP/GaAs HBTs, showing a significant increase of the safe operating area due to collector profile optimization.