0.4-μm InP/InGaAs DHBT with a 380-GHz ${f_{T}}$, > 600-GHz $f_{\max}$ and BVCE0 > 4.5 V

We report on a 0.4-μιm emitter width composition-graded-base InP/InGaAs/InP DHBT technology featuring a current gain cutoff frequency (
${f_{T}}$
) and a maximum oscillation frequency (
$f_{\max}$
) of 380 GHz and 605 GHz, respectively. The DHBTs demonstrate a maximum static current gain of 29 and a common-emitter breakdown voltage of 4.7 V. RF performances above 600 GHz were achieved through emitter size scaling and base contact width shrinking. Further investigations on measurements were performed by comparing three VNA calibration methods as well as through extraction of small-signal parameters over the 110 GHz measurement range.