Physical origins of nonlinearity in InP double heterojunction bipolar transistors

Two tone inter-modulation distortion measurements were performed at 18 GHz to characterize the nonlinearity of Type-I InP/InGaAs/InP and Type-I/II AlInP/GaAsSb/InP double heterojunction bipolar transistors (DHBTs). Two-dimensional hydrodynamic (HD) simulations were also performed, showing that the base push-out and charge accumulation effects are the dominant physical origins of nonlinearity for the Type-I DHBT at high current densities. Comparatively, the Type-I/II DHBT exhibits no such effects. Hence, we conclude that DHBTs having a Type-I/II energy band alignment will have an inherent linearity advantage compared to DHBTs with the Type-I energy band alignment.