Exploring the optical property of InAs_1−xSb_x-based nBn structures for high-temperature mid-wave infrared detection

InAs_0.9Sb_0.1-based nBn structures for mid-wave infrared detection are designed and prepared by molecular beam epitaxy. The structural, electrical, and optical properties are characterized, based on which the density-functional theory calculation is carried out by combining with the hybrid HSE06 exchange-correlation function. The results demonstrate that (i) the calculated bandgap for InAs_0.9Sb_0.1 is well consistent with that of optical spectroscopies (∼266 meV, or a cutoff wavelength of ∼4.66 μm), suggesting the practical effectivity of the theoretical model; (ii) the valence band offset of the unbiased InAs_0.9Sb_0.1/AlAs_0.1Sb_0.9 nBn structure is determined as ∼105 meV, with ignorable influence on the hole transport of the devices by considering the rather low dark current when working at a high temperature of ∼150 K; and (iii) the conduction band offset of InAs_0.9Sb_0.1/GaSb is roughly ∼0.6 eV. This work not only provides a strategy for effectively evaluating the InAs_1−xSb_x bandgap both theoretically and experimentally but also offers a more reliable basis for fabricating high-performance mid-infrared detectors with high operating temperatures.