Manufacturability and flexibility of type-II InAs/GaSb superlattice detectors for infrared imaging

In recent years InAs/InGaAsSb Type-II superlattices (T2SLs) have proven to be excellent material for high end infrared (IR) detectors and are now competing with the traditional state-of-the-art technologies. One of the major advantages of this technology is the good manufacturability due to mature V/III-processing. Another advantage is the flexibility to tailor the cut-off wavelength to any desired detection wavelength in the IR wavelength region. In this paper, we will show proof of the good manufacturability of these detectors by presenting statistics from the production of midwave 320 × 256 InAs/GaSb focal plane arrays (FPAs). Statistics show that temporal and spatial NETD levels of 12 mK and 4 mK, respectively, are obtained repeatedly, with f/2 optics and 8 ms integration time. Studies on the image stability of T2SL detectors show that no deterioration of image quality over time can be observed. It is also shown that the non-uniformity correction remains stable even after repeated detector temperature cycles. When studied over a large scene temperature, the spatial noise is still less than 60 % of the temporal noise. Furthermore, we will demonstrate the flexibility and usability of this detector design, which has been tailored for cut-off wavelengths from 2.4 mm to 12.1 mm with only minor changes in the thicknesses of the individual superlattice layers.