200-nm InGaAs/InP type I DHBT employing a dual-sidewall emitter process demonstrating ƒmax ≫ 800 GHz and ƒτ = 360 GHz

Type I InP/InGaAs/InP double heterojunction bipolar transistors were fabricated using a simple mesa structure, where emitter junction widths have been scaled from 250 nm to 200 nm. These devices exhibit f _max in excess of 800 GHz, and f _tau = 360 GHz. Greater than fifty percent device yield was obtained by employing two 25 nm SiN_x sidewalls to protect and anchor the refractory metal emitter contact to the emitter semiconductor. A hybrid dry and wet etch process is used to form a vertical emitter mesa, causing reductions in both the emitter-base gap resistance R_gap and the spreading resistance beneath the emitter R_b,spread, leading to an expected and observed increase in f _max. Peak HBT current gains beta ap 21-33, BV_ceo ~ 4 V, BV_cbo ~ 5 V, and J_e at low V_cb is over 10 mA/mum².