STRAIN RELAXATION MORPHOLOGIES OF IIA-FLUORIDES AND LEAD-CHALCOGENIDE LAYERS ON SI(111)

The thermal mismatch strain introduced by the different thermal expansion of fluorides, IV-VI materials and the Si(111) substrate is relieved by glide of dislocations in the primary (100)(110) glide system with glide planes inclined to the surface. The morphology of the resulting straight slip steps is revealed with atomic force microscopy (AFM) for the fluorides and scanning tunneling microscopy (STM) for the IV-VI materials. The number of observed dislocation step lines agrees with the calculated thermal strain relaxation.