INFRARED MULTIPLE-QUANTUM-WELL PHOTOTRANSISTOR

The multiple-quantum-well (MQW) phototransistor is considered theoreti cally. The MQW phototransistor utilizes intersub-band optical absorpti on and exhibits giant photocurrent gain which can lead to very high re sponsivity and detectivity. This effect is due to the thermionic injec tion of hot electrons across the emitter barrier and fast electron tra nsit through the MQW base. An analytic theory of the MQW phototransist or utilizing parameters evaluated by Monte Carlo simulation is propose d. Transition from near ballistic hot electron transport to diffusive transport decreases the responsivity but its value can be significant in this case as well.