Infrared imaging arrays based on superlattice photodiodes

We report on the status of focal plane arrays (FPAs) based on GaSb/InAs type-II superlattice diodes grown by molecular beam epitaxy (MBE) and designed for infrared absorption in the 2-5μm and 8-10μm bands. Recent LWIR devices have produced differential resistance-area product greater than 100 Ohmcm² at 80K with a long wavelength cutoff of approximately 10μm. The measured quantum efficiency of these front-side illuminated devices is close to 25% in the 8-9 μm range. MWIR devices have produced detectivities as high as 8x10¹³ Jones with a differential resistance-area product greater than 3x10⁷ Ohmcm² at 80K with a long wavelength cutoff of approximately 3.7μm. The measured quantum efficiency of these front-side illuminated MWIR devices is close to 40% in the 2-3μm range at low temperature and increases to over 60% near room temperature. Initial results on SiO₂ and epitaxial-regrowth based passivation techniques are also presented, as well as images from the first lot of 1kx1k MWIR arrays and our latest 256x256 LWIR arrays.