InGaP/GaAsSb/InGaAsSb/InP Double Heterojunction Bipolar Transistors With Record f t of 813 GHz

Abstract

We fabricated InGaP/GaAsSb/InGaAsSb/InP double heterojunction bipolar transistors (DHBTs) with an aggressive lateral and vertical scaling technology to improve the current gain cutoff frequency ( ${f}_{\text {t}}$ ) further. A 13-nm-thick GaAsSb/InGaAsSb base and a 40-nm-thick InP collector are used to reduce electron transit time. In addition, the width of the base electrode on each side of the emitter is reduced to about 0.05 $\mu \text{m}$ to suppress increases in parasitic collector capacitance. A fabricated DHBT with the emitter size of 0.24 $\mu \text{m}\,\,\times7.8\,\,\mu \text{m}$ exhibits maximum differential current gain of ~95 and collector-emitter breakdown voltage of 2.6 V. At a collector current density of 18 mA/ $\mu \text{m}^{{2}}$ , the DHBT exhibits ${f}_{\text {t}}$ of 813 GHz, which is the highest among all types of transistors measured at a room temperature.