A novel device-the quantum-dot infrared phototransistor (QDIP)-is prop
osed and considered theoretically. The QDIP utilizes intersubband elec
tron transitions from the bound states. The dark current and sensitivi
ty are calculated using a proposed analytical model of the QDIP. It is
shown that the QDIP can exhibit low dark current, high photoelectric
gain and sensitivity surpassing the characteristics of other intersubb
and photodetectors.