High performance photodiodes based on InAs/InAsSb type-II superlattices for very long wavelength infrared detection

Very long wavelength infrared photodetectors based on InAs/InAsSb type-II superlattices are demonstrated on GaSb substrate. A heterostructure photodiode was grown with 50% cut-off wavelength of 14.6 μm. At 77 K, the photodiode exhibited a peak responsivity of 4.8 A/W, corresponding to a quantum efficiency of 46% at −300 mV bias voltage from front side illumination without antireflective coating. With the dark current density of 0.7 A/cm2, it provided a specific detectivity of 1.4 × 1010 Jones. The device performance was investigated as a function of operating temperature, revealing a very stable optical response and a background limited performance below 50 K.