High performance long wavelength infrared mega-pixel focal plane array based on type-II superlattices

A large format $1k×1k$ focal plane array (FPA) is realized using type-II superlattice photodiodes for long wavelength infrared detection. Material growth on a 3 in. GaSb substrate exhibits a 50% cutoff wavelength of $11μm$ across the entire wafer. The FPA shows excellent imaging. Noise equivalent temperature differences of 23.6 mK at 81 K and 22.5 mK at 68 K are achieved with an integration time of 0.13 ms, a 300 K background and f/4 optics. We report a dark current density of $3.3×10−4Acm−2$ and differential resistance-area product at zero bias $R0A$ of $166Ωcm2$ at 81 K, and $5.1×10−5Acm−2$ and $1286Ωcm2$⁠, respectively, at 68 K. The quantum efficiency obtained is 78%.