Observation of thermal-misfit strain relaxation in a PbTe semiconductor grown on Cd0.96Zn0.04Te(1?1?1)

The thermal-misfit strain relaxation in epitaxial PbTe grown on Cd0.96Zn0.04Te(1 1 1) substrates has been studied by the combined characterization of atomic force microscopy and high-resolution transmission electron microscopy. It is shown that the strain relaxes by the movement of dislocations in the 1 1 0–{1 0 0} primary glide system and leaves straight slip steps on the surface. The thermal-misfit strain relaxation is greatly affected by the growth temperature and post-growth cooling rate. Post-growth treatment with a slower cooling rate improves the crystalline quality of PbTe grown on Cd0.96Zn0.04Te(1 1 1). Because of the easy dislocation glide down to the interface in the 1 1 0–{1 0 0} primary glide system, PbTe/Cd0.96Zn0.04Te(1 1 1) heterostructures exhibit good crystal and optical qualities, which indicate that PbTe/CdZnTe heterostructures may become a promising candidate for the fabrication of PbTe-based mid-infrared optoelectronic devices.