InAsSb pillars for multispectral long-wavelength infrared absorption

InAsSb pillars were investigated for multispectral photodetection in the long wavelength infrared (LWIR) region. An InAs0.19Sb0.81 thin film was successfully grown on Si (100) substrate, utilizing an AlSb buffer layer to alleviate the large lattice mismatch. X-ray diffraction studies showed a majority [100] orientation of the as-grown films, with minor orientations arising as a result of twinning. Arrays of InAsSb pillars with diameters ranging from 1700 nm to 4000 nm were fabricated by a top-down reactive ion etching process. The arrays showed resonant optical absorption peaks in the LWIR region from 8 to 16 μm wavelength, dependent on the pillar diameter. The peak absorptance wavelength increased by 0.46 μm for each 100 nm increase in pillar diameter, demonstrating the multispectral tunability of such arrays.