InAs 1-x Sb x material with an alloy composition of the absorber layer adjusted to achieve 200K cutoff wavelengths in the 5 µm range has been grown. Compound-barrier (CB) detectors were fabricated and tested for optical response and J dark -V d measurements were acquired as a function of temperature. Based on absorption coefficient information in the literature and spectral response measurements of the midwave infrared (MWIR) nCBn detectors, an absorption coefficient formula α(Ε, x, T) is proposed.Since the presently suggested absorption coefficient is based on limited data, additional measurements of material and detectors with different x values and as a function of temperature should refine the absorption coefficient, providing a more accurate parametrization. Material electronic structures were computed using a k•p formalism. From the band structure, dark current density (J dark ) as a function of bias (V d ) and temperature (T) were calculated and matched to J dark -V d at fixed T and J dark -T at constant V d curves. There is a good match between simulation and data over a wide range of bias, but discrepancies that are not presently understood exist near zero bias.a. e-mail: arvind.d'

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