On the structural characterization of InAs/GaSb type-II superlattices: The effect of interfaces for fixed layer thicknesses

• Growth conditions are discussed in detail for type-II InAs/GaSb superlattices.
• Interface thicknesses are systematically changed for fixed InAs and GaSb layers.
• Shown that in-plane mismatch is inversely proportional to the interface thickness
• The mismatch is precisely controlled by engineering the InSb-like interfaces.

We report on the detailed epitaxial growth conditions for type-II InAs/GaSb superlattice (SL) structures designed for mid-wave infrared detection. The mismatch between the GaSb buffer and the SL is precisely controlled by engineering the InSb-like interfaces for fixed InAs and GaSb layer thicknesses in the SL. High resolution X-ray diffraction and cross-sectional high resolution transmission electron microscopy analyses were performed to determine the mismatch and the thicknesses. It was shown that the in-plane lattice mismatch to the GaSb buffer is inversely proportional to the interface thickness for the samples presented here. The effect of the interfaces on the structure was also confirmed by room temperature transmission measurements: features were red-shifted as the interface thickness is increased.