Quantum-well infrared phototransistor with pHEMT structure

A quantum-well infrared phototransistor with a pseudomorphic high-electron mobility transistor (pHEMT) structure is presented. The proposed phototransistor uses four periods of a GaAs/Al/sub 0.3/Ga/sub 0.7/As (50 /spl Aring//120 /spl Aring/) quantum-well absorption region, as well as an In/sub 0.15/Ga/sub 0.85/As quantum well conducting channel under the absorption layer. The phototransistor shows a large responsivity of 140 A/W around 6 μm at 23 K (for a cutoff wavelength of 7.5 μm). The relation between the photoconductive gain and the transconductance of the pHEMT structure is also investigated.