Kirk Effect in Type-II InP/GaAsSb DHBTs with a Collector Doping Spike

Abstract

The Kirk effect in type-II InP/GaAsSb DHBTs with spike-doped collectors is studied experimentally and theoretically. Accurate two-dimensional hydrodynamic (2D-HD) physical device simulations show that the Kirk threshold current in type-II DHBTs depends on negative conduction band offset (DeltaEC) and is a function of the doping spike position in the InP collector. The optimal collector design can significantly increase the Kirk current limit and the peak fT, without significantly reducing BVCEO.