We report a high performance long-wavelength IR dual-band imager based on type-II superlattices with 100% cutoff wavelengths at 9.5 μm (blue channel) and 13 μm (red channel). Test pixels reveal background-limited behavior with specific detectivities as high as ~5×10¹¹ Jones at 7.9 μm in the blue channel and ~1×10¹¹ Jones at 10.2 μm in the red channel at 77 K. These performances were attributed to low dark currents thanks to the M-barrier and Fabry-Perot enhanced quantum efficiencies despite using thin 2 μm absorbing regions. In the imager, the high signal-to-noise ratio contributed to median noise equivalent temperature differences of ~20 milli-Kelvin for both channels with integration times on the order of 0.5 ms, making it suitable for high speed applications.
We report a two-color mid-wave infrared (MWIR) and long-wave infrared (LWIR) co-located detector with 3 μm active region thickness per channel that is highly selective and can perform under high operating temperatures for the MWIR band. Under back-side illumination, a temperature evolution study of the MWIR detector's electro-optical performance found the 300 K background-limit with 2π field-of-view to be achieved below operating temperatures of 160 K, at which the temperature's 50% cutoff wavelength was 5.2 μm. The measured current reached the system limit of 0.1 pA at 110 K for 30 μm pixel-sized diodes. At 77 K, where the LWIR channel operated with a 50% cutoff wavelength at 11.2 μm, an LWIR selectivity of ~17% was achieved in the MWIR wave band between 3 and 4.7 μm, making the detector highly selective.
An InAs/GaSb type-II superlattice-based mid-wavelength infrared (MWIR) 320×256 unipolar focal plane array (FPA) using pMp architecture exhibited excellent infrared image from 81 to 150 K and ∼98% operability, which illustrated the possibility for high operation temperature application. At 150 K and -50 mV operation bias, the 27 μm pixels exhibited dark current density to be 1.2×10(-5) A/cm(2), with 50% cutoff wavelength of 4.9 μm, quantum efficiency of 67% at peak responsivity (4.6 μm), and specific detectivity of 1.2×10(12) Jones. At 90 K and below, the 27 μm pixels exhibited system limited dark current density, which is below 1×10(-9) A/cm(2), and specific detectivity of 1.5×10(14) Jones. From 81 to 100 K, the FPA showed ∼11 mK NEDT by using F/2.3 optics and a 9.69 ms integration time.
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