Performance and advantages of BICFETs versus HBTs

The BICFET, a new form of bipolar transistor that offers superior performance for III-V bipolar integrated circuits and several unique advantages over known approaches for optoelectronic integration, is described. The BICFET does not have a base. Instead, the control (or biasing) charge is confined to the inversion channel at a heterojunction interface which is accessed by a source self-aligned to the emitter. The channel is induced by a charge sheet located in the depleted barrier section of the emitter. The mobility of the channel is high (and thus its resistance R_IN is low) because the narrow-band semiconductor at the interface is undoped. The BICFET does not have charge storage or recombination in a neutral base, and it has the potential for very high speed due its low input capacitance and the enhanced carrier velocity in the collector. The first operation of the N-channel BICFET is reported here. The base-resistance, current-gain, and input-capacitance characteristics of the BICFET are compared to those of the HBT, and BICFET is found to be an attractive structure for circumventing the problems of charge storage and carrier recombination in the HBT