Sub-300 nm InGaAs/InP Type-I DHBTs with a 150 nm collector, 30 nm base demonstrating 755 GHz fmax and 416 GHz fτ

We report InP/InGaAs/InP double heterojunction bipolar transistors (DHBT) fabricated using a simple mesa structure. The devices employ a 30 nm highly doped InGaAs base and a 150 nm InP collector containing an InGaAs/InAIAs superlattice grade. These devices exhibit a maximum f(max) = 755 GHz with a 416 GHz f(tau). This is the highest f(max) reported for a mesa HBT. Through the use of i-line lithography, the emitter junctions have been scaled from 500-600 nm down to 250-300 mn - all while maintaining similar collector to emitter area ratios. Because of the subsequent reduction to the base spreading resistance underneath the emitter R-b,R-spread and increased radial heat How from the narrower junction, significant increases to f(max) and reductions in device thermal resistance theta(JA) are expected and observed. The HBT current gain beta approximate to 24-35, BVceo= 4.60 V, BVcbo = 5.34 V, and the devices operate up to 20 mW/mu m(2) before self-heating is observed to affect the DC characteristics.