A modulation-doped longwave infrared quantum dot photodetector with high photoresponsivity

An InAs–InGaAs quantum dot (QD) longwave infrared (LWIR) photodetector (QDIP) with a peak wavelength of 8.2 µ m is presented. The QDIP has modulation-doped QD active layers. At 77 K, the QDIP showed high photoresponsivities of 5.4 A W −1 and 3.6 A W −1 at biases of −0.8 V and 0.6 V, respectively. A peak photodetectivity of 7.8 × 10 9 cm Hz 1/2 W −1 was obtained at 77 K in an IR detector compatible package.