Numerical simulation of GaAs/GaAlAs heterojunction bipolar transistors

A numerical analysis program for the one-dimensional simulation of GaAs/GaAlAs heterojunction bipolar transistors is described. Calculations for a representative transistor structure indicate that a cutoff frequency of 100 GHz is obtainable. To attain such a high value, the transistor design incorporated a graded-bandgap base region and relatively high emitter doping (5 x 10 to the 17th/cu cm), and the device was operated at high current density (50,000 A/sq cm). Transient electron velocity overshoot effects were also included.