X-ray reciprocal space mapping of a (112) oriented HgTe/Hg0.1Cd0.9Te superlattice

Strain in a HgTe/Hg0.1Cd0.9Te superlattice grown on (112)B Cd0.96Zn0.04Te substrate has been investigated by x-ray reciprocal space mapping. It is shown that the shear strain in the superlattice results in monoclinic unit cells, whereas the cubic symmetry of the substrate is retained. The reciprocal lattice points of the superlattice are shifted by the shear strain such that the conventional analysis fails to interpret them correctly. Instead, reciprocal space maps should be constructed for two azimuths in opposite directions and analyzed simultaneously in a coordinate system with nonorthogonal axes. The shear strain is obtained from the angle between the [1¯1¯1] directions of the superlattice and the substrate. After a position correction taking the measured shear strain into account, longitudinal strains are calculated with conventional methods.