High-current-gain InP DHBTs with a passivation ledge demonstrating ft and fmax of over 440 GHz

Abstract

This paper reports current gain and high-frequency characteristics of InP DHBTs with a passivation ledge and various emitter sizes. With the passivation ledge, current gain of over 40 is maintained even for a 0.25-μm-emitter HBT. The f_t is over 420 GHz for HBTs with emitters ranging from 0.25 to 0.5 μm. On the other hand, the f_max greatly increases from 320 to 440 GHz with decreasing emitter width from 0.5 to 0.25 μm. These results indicate that the 0.25-μm-emitter HBT exhibits balanced high-frequency performance (f_t= 449 GHz and f_max= 440 GHz) while maintaining a current gain of over 40.