Modelling of gain control in SiGe HBTs and Si bipolar transistors by Ge incorporation in the polysilicon emitter

V.D.Kunz, C.H. de Groot, I.M.Anteney, A.I.Abdul-Rahim, S.Hall, P.Ashburn
University of Southampton, UK

Keywords: polySiGe emitter, bipolar transistor, gain control

Abstract:
In SiGe HBTs high values of fT are achieved by using aggressive Ge profiles in the base. A side effect is very high gains, which can lead to a degradation of BVCEO. This paper investigates Ge incorporation in polysilicon emitters to give gain control independent of the base Ge profile. A model is developed illustrating the reduced gain from Ge incorporation and increased gain from the interfacial oxide layer.

NSTI Nanotech 2003 Conference Technical Program Abstract