Temperature-dependent photoluminescence of InSb/InAs nanostructures with InSb thickness in the above-monolayer range

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Photoluminescence (PL) properties of type-II InSb/InAs periodic nanostructures containing above-monolayer (ML)-thick InSb insertions, grown by molecular beam epitaxy, are studied by using an FTIR spectrometer in wide temperature range. The samples exhibit bright PL in the 3.5–5.5 μm range, which is attributed to recombination of holes localized in InSb with electrons accumulated nearby in the InAs matrix. An increase in the InSb nominal thickness from 1 ML to 1.6 ML results in an increase of the PL peak wavelength up to 5.5 μm (300 K), and significantly improves luminescence intensity at 300 K due to a twice larger energy of hole localization. The InSb/InAs nanostructures also demonstrate an anomalous ‘blue’ shift of the PL peak energy as the temperature increases in the 12–80 K range, which is attributed to the thermally induced population of localized states in the InSb insertions, emerging due to composition/thickness fluctuations. Sb segregation in the cap InAs barrier smooths the potential inhomogeneities in the insertions, which reduces the broadening parameter.