Conduction intersubband (In,Ga)As/GaAs quantum dot infrared photodetectors

The authors report a 40-period (In,Ga)As/GaAs normal-incidence quantum dot infrared photodetector operating in the wavelength range 8-14 μm. A primary intersubband transition peak is observed at a wavelength of 12.5 μm (E₀→E₁), and a secondary peak at 11.3 μm (E₀→E₂). The measured intersubband energy spacing is in good agreement with calculations. The normal-incidence peak responsivity at the bias voltage of -6 V is ~0.17 A/W. The background-limited performance temperature of our devices is found to be 62 K