Direct observation of dislocations in GaP crystals

Abstract

The bi-refringent method is applied to investigate dislocations in GaP single crystals. The results are compared to those obtained by X-ray topography, electroluminescence, and electron beam induced conductivity. It is shown that the bi-refringent method reveals slip lines, lattice stresses, as well as single dislocations, with a high contrast depending on the orientation of the sample with respect to the polarization plane of the incident light. The method enables the resolution of single dislocations in crystals with high dislocation densities and the distinction between decorated and undecorated dislocations. Furthermore, dislocations in an epitaxial layer can be observed separately from those in the substrate material.