MWIR InAsSb XB n n detector (bariode) arrays operating at 150K

Abstract

The XB_n<i>n</i> high operating temperature (HOT) detector project at SCD is aimed at developing a HOT (~150K) mid-wave infrared (MWIR) detector array, based on InAsSb/AlSbAs barrier detector or "bariode" device elements. The essential principle of the XB_n<i>n</i> bariode architecture is to suppress the Generation-Recombination contribution to the dark current by ensuring that the depletion region of the device is contained inside a large bandgap <i>n</i>-type barrier layer (BL) and excluded from the narrow bandgap <i>n</i>-type active layer (AL). The band profile of the XB_n<i>n</i> device leads to effective blocking of electron transport across the BL while maintaining a free path for the holes, thus assuring a high internal quantum efficiency (QE). Our devices exhibit a very large minority carrier lifetime (~700 ns), leading to a very low dark current of &lt;10^-6 A cm^-2 at 150K, which is essentially diffusion limited. We compare bariode devices with both a <i>p</i>-type GaSb contact layer (CL) and an n-type InAsSb CL (termed C_pB_n<i>n</i> and <i>n</i>B_n<i>n</i>, respectively). Apart from a ~0.3V shift in the operating bias, the optical and electrical properties of both architectures are virtually identical, demonstrating the generic nature of the XB_n<i>n</i> barrier detector family. We have fabricated FPAs from <i>n</i>B_n<i>n</i> bariode arrays bonded both to a 320×256, 30 &mu;m pitch Read-Out Integrated Circuit (ROIC) and a 640×512, 15 &mu;m pitch ROIC. For lattice matched FPAs the cut-off wavelength at &gt;50% of maximum response is ~ 4.1 &mu;m. We show an image registered at 150K with a 640×512/15 &mu;m Pelican FPA, using f/3.2 optics. The operability at 150K is &gt;99.5% and the measured NETD, limited only by shot and Read-Out noise, is 20 mK for a 22 ms integration time. At this f/number, the detector has a background limited performance (BLIP) up to ~165K.