InGaAs/InP DHBTs with a 75nm Collector, 20nm base Demonstrating 544 GHz ft, BVCEO = 3.2V, and BVCBO = 3.4V
We report InP/InGaAs/InP double heterojunction bipolar transistors (DHBT) fabricated using a conventional mesa structure. The devices employ a 20 nm highly doped InGaAs base and a 75 nm InP collector containing an InGaAs/InAlAs superlattice grade. These devices exhibit a maximum fτ = 544 GHz with a 347 GHz fmax, which is the highest fτ for an InP DHBT, and highest fτ at a 75 nm collector thickness for any HBT. The devices have been scaled vertically for reduced base and collector electron transit times, and the base-collector mesa has been kept narrow to minimize the capacitance Ccb associated with thinner collectors. The current gain β ≈ 50, BVCEO = 3.2 V, BVCBO = 3.4 V, and the devices operate up to 24 mW/μm (failing at Je = 12 mA/μm , Vce = 2.0 V, ∆Tfailure ≈ 348 K).