Molecular beam epitaxial growth of InAsSb strained layer superlattices. Can nature do it better?

Molecular beam epitaxial growth of a normally homogeneous InAs _0.5Sb_0.5 alloy below 430 °C results in its coherent phase separation into platelets of two different alloy compositions with tetragonally distorted crystal lattices. This produces a ''natural'' strained layer superlattice (n-SLS) with clearly defined interfaces modulated in the [001] growth direction. A description of the n-SLS growth mode in InAsSb is outlined, and the optical response of a n-SLS structure, which extends to 12.5 μm-considerably further than that of a homogeneous InAs_0.5Sb _0.5 layer (8.9 μm)-is reported.