Ingaas/Inp Dhbts With Emitter And Base Defined Through Electron-Beam Lithography For Reduced C-Cb And Increased Rf Cut-Off Frequency

InGaAs/InP DHBTs are fabricated using electron-beam lithography to define the emitter and base mesas. Emitter mesas 150 nm wide, and base mesas with < 25 nm misalignment to the emitter have been developed. Emitter contacts are prepared through blanket, refractory metal evaporation to obtain emitter contact resistivity rho(ex) = 2 Omega.mu m(2). This low record resistivity, combined with the narrow emitter and base mesas, enables device RF performance of simultaneous f(r) and f(max) of 530 GHz and 750 GHz, respectively, at a power density of > 40 mW/mu m(2).[GRAPHICS]A top-view SEM micrograph of the electron-beam lithography-defined emitter and base contacts, shows narrow mesas and small misalignment between the two layers. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim