Geometrical scaling effects in InP/InGaAs double heterojunction bipolar transistor

The effect of emitter size of InP/InGaAs hetero-junction bipolar transistors (HBTs) on the DC and AC characteristics is investigated. It is found that the gain of the devices decreases with increase in the perimeter to area ratio of the emitter. The cutoff frequency f_T varies with different emitter width, and emitter length. The extracted capacitance and the resistance r_C are also presented.