Evaluation of aluminum mole fraction for controlled thermal behavior of AlGaAs/GaAs HBT

The thermal behavior of AlGaAs/GaAs HBT was analyzed. The thermal stability improves with increasing Al mole fraction. The turn-on voltage of the device increases as the mole fraction which results in less power dissipation and hence better thermal stability. Two dimensional analysis shows much reduced temperatures compared to 1D since it accommodates the lateral dissipation of heat. Multi-emitter finger heterojunction transistor exhibits non-uniform temperature distribution across the device. To reduce the peak temperatures, device layouts with narrower emitters and/or wider spacing between the emitters are used.