Development of MWIR and LWIR nBn photodetectors at i3system

In modern infrared systems, barrier infrared detectors (BIRDs) have been widely used because a barrier is effective in reducing dark current by Shockley-Reed-Hall (SRH) process. Many researches have been studied on design of the barrier that prevents majority carrier flow and permits minority carrier flow. In this paper, we have studied on type-II superlattice (T2SL) nBn detectors having an unipolar barrier, where design and epi. growth are relatively simple for MWIR high operating temperature (HOT) and cooled LWIR detectors. InAs/InAsSb nBn for MWIR detection and InAs/GaSb nBn for LWIR detection were designed and fabricated. The fabricated MWIR and LWIR devices showed a dark current density of ≤ 2×10^-6 A/cm² at 150 K and ≤ 5×10^-6 A/cm² at 80 K, respectively. Also, 15 μm VGA MWIR and LWIR FPAs showed excellent performance with an average noise equivalent temperature difference (NETD) of ≤ 20 mK and operability of 99.5 % at 150 K and 80 K, respectively. MWIR HOT detector exhibited measured NETD similar to theoretical NETD considering dark current. And 10 μm SXGA HOT MWIR detector for high resolution imaging showed perfornance with an average NETD of ≤ 25 mK and operability of ≥99.5 % up to 130 K.