LWIP: a long-wavelength infra-red phototransistor

A novel device is proposed that combines the principles, functions and advantages of a quantum-well infra-red photodiode and a phototransistor for detection of long wavelength infra-red radiation (6-20 mu m). This device is called an LWIP: a long-wavelength infra-red phototransistor. Si_1-xGe_x/Si is an ideal candidate for this heterostructure. An optimised device is expected to exhibit very low leakage/dark current, high gain and high detectivity, and has the potential of operating at a relatively higher temperature.