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 11 μm 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 3.3×10−4 A cm−2 and differential resistance-area product at zero bias R0A of 166 Ω cm2 at 81 K, and 5.1×10−5 A cm−2 and 1286 Ω cm2, respectively, at 68 K. The quantum efficiency obtained is 78%.