A model was developed which described the reflectance-difference spectra, of zinc-blende semiconductors, which were due to the strains that were introduced by and 60 dislocations. It was shown that, near to the semiconductor surface (as a result of the loss of lattice periodicity), dislocations produced an anisotropic average strain that changed the symmetry from cubic to orthorhombic; thus leading to a reflectance anisotropy. Expressions were obtained, for reflectance-difference spectra, which predicted the observation of first-derivative reflectance-difference line-shapes; provided that the strain-induced energy shifts were small when compared with spectra broadening energies. A study was also made of the reflectance-difference spectra of (100) semi-insulating material in the 1.2 to 5.5eV energy range, and this showed that such spectra comprised a component that was well described by the present model.
L.F.Lastras-MartÃnez, A.Lastras-MartÃnez: Physical Review B, 1996, 54[15], 10726