High-responsivity intersubband infrared photodetector usingInGaAsP/InP superlattice

A 4-7-μm infrared detector made of an InGaAsP/InP short-period superlattice is demonstrated with materials grown by metalorganic chemical vapor deposition (MOCVD). A single current blocking layer of InP is used to reduce the dark current. At 40 K, the detector shows a low dark current of less than 4 pA at a bias voltage of 4 V. At 35 K, a peak responsivity of 4.0 A/W is obtained at 5.6 μm at a bias of 1 V