Electrooptical Characterization of MWIR InAsSb Detectors

InAs 1− x Sb x material with an alloy composition of the absorber layer adjusted to achieve 200-K cutoff wavelengths in the 5- μ m range has been grown. Compound-barrier (CB) detectors were fabricated and tested for optical response, and J dark – V d measurements were taken 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 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 ) was calculated and matched to J dark – V d curves at fixed T and J dark – T curves at constant V d . 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.