Scaling of InP/GaAsSb DHBTs: A Simultaneous $f_{\text{T}}/f_{\text{MAX}}=463/829$ GHz in a $10\ \mu \text{m}$ Long Emitter

The scaling behavior of Type-II InP/GaAsSb double heterojunction bipolar transistors (DHBTs) is studied and a 10 μm long emitter with cutoff frequencies of fT/fMAX=463/829 GHz and is demonstrated. Such a high fMAX was made possible by aggressive lateral scaling of the base-collector (BC) mesa which helps to reduce the extrinsic BC capacitance. The limitations in furthering the lateral scaling for these devices are examined. The present transistors show the highest fMAX for a 10 μm long emitter for any HBT, indicating the excellent scaling properties of Type-II DHBTs.