Ge-profile design for improved linearity of SiGe double HBTs

The influence of Ge-profile design on SiGe HBT linearity-harmonic distortion has been quantified using finite element physical device simulation. It was demonstrated that proper Ge-profile tailoring allows the linearity to be improved for both low- and high-current operation. High injection heterojunction barrier effects are shown to have a significant influence on the higher order harmonics. The influence of the Ge-profile design on linearity was found to be comparable to the influence from the epitaxial collector doping profile.