FRACS (fully radiative current path structure)-A high speed bipolar transistor with sub-0.1 mu m emitter

It is shown that in the fully radiative current path structure (FRACS) transistor the maximum cutoff frequency (f/sub T/) is enhanced by the equivalent drift field induced in the base by the radiative diffusion current from a small emitter-base (E-B) junction to a large collector-base (C-B) junction. The f/sub T/ can be increased by reducing the emitter size as well as by reducing the base width. Theoretical analysis and experimental results show that the f/sub T/ is enhanced as the emitter becomes smaller. FRACS is thus a suitable structure for future sub-0.1- mu m emitter transistors.<>