Two color InAs/InGaAs dots-in-a-well detector with background-limited performance at 91 K

Normal incidence long wave infrared (λc∼9 μm) InAs/In0.15Ga0.85As dots-in-a-well detectors with background limited performance at 91 K, under f#1.7 300 K background irradiance, are reported. Two distinct peaks (λp1∼4.2 μm and λp2∼7.6 μm) are observed in the spectral response, which could possibly be due to a bound-to-continuum transition and a bound-to-bound transition, respectively. The operating wavelength of the detector can be varied by changing the width of the quantum well surrounding the quantum dots. Using calibrated blackbody measurements, the peak responsivity of the detector is measured to be 0.73 A/W (Vb=−1.7 V at T=60 K).