Charge sensitive infrared phototransistor for 45   μ m wavelength

The detection wavelength of charge-sensitive infrared phototransistors (CSIPs), originally developed for 15 μ m wavelength radiation, is expanded to longer wavelengths of ∼ 45 μ m . The CSIPs are fabricated on GaAs/AlGaAs crystals with bilayer two-dimensional electron gas. Photoresponse at targeted wavelengths is confirmed. Low quantum efficiency of photoresponse, on the order of 10 − 4 , has been ascribed to electron traps (Al-O complex) contained in an AlGaAs barrier layer. Several possible approaches for improving the detector performance are suggested.