High-frequency submicrometer Al/sub 0.48/In/sub 0.52/As/In/sub 0.53/Ga/sub 0.47/As heterostructure bipolar transistors

The high speed scaling of an Al/sub 0.48/In/sub 0.52/As/In/sub 0.53/Ga/sub 0.47/As submicrometer heterostructure bipolar transistor (HBT) is presented. Transistors with emitter dimensions of 0.5*11 and 3.5*3.5 mu m/sup 2/ exhibit unity current-gain cutoff frequencies of 63 and 70 GHz, respectively. Emitter current density greater than 3.3*10/sup 5/ A/cm/sup 2/ is demonstrated in a submicrometer AlInAs/InGaAs HBT. The analysis shows that the device speed is limited by the parasitic collector charging time.>