Variable-gain inversion layer emitter phototransistor in CMOS technology

The vertical bipolar phototransistor in CMOS technology employing the inversion emitter concept has been analysed by simulation and experiment. It is found that the inversion emitter substantially increases current gain, particularly at low current levels, which yields a high output photo-current. In addition, current gain and photo-current magnitude can be controlled by the external gate voltage which gives the potential for a number of novel applications.