600 GHz InP/GaAsSb/InP DHBTs grown by MOCVD with a Ga(As,Sb) graded-base and fT x BVceo > 2.5 THz-V at room temperature

Abstract

We describe the realization of ternary base InP/Ga(As,Sb) DHBTs, where the grading is implemented by ramping the base As/Sb composition ratio from the collector to the emitter side: this enables a cutoff frequency f T of 603 GHz at room temperature with a breakdown voltage BV CEO = 4.2 V, for a record f T xBV CEO product of 2.53 THz-V. Device performance improves further with cooling to reach f T ≫ 700 GHz with BV CEO = 4.4 V at 5K. To the best of our knowledge, this represents the highest f T ever reported for a DHBT of any kind. The f T xBV CEO ≫ 3.10 THz-V at 5 K is also unprecedented.