Reflection electron imaging of free surfaces and surface/dislocation interactions

Abstract

The technique of reflection electron microscopy (REM) has been used to image the free surfaces and the general case of surface/dislocation interaction. The displacement and rotation fields for an arbitrary dislocation meeting a perfect, truncated surface of a semi-infinite elastically isotropic solid at an arbitrary angle have been obtained and used to simulate the REM dislocation images. The results are compared with those for a free surface, taking into account the extra stress relaxation of the surface atoms resulting from the surface/dislocation interaction. The effects of the free surface on the displacement and rotation fields associated with dislocations emerging at the surface are significant; and to match the REM dislocation images with the computed images, the effects of surface/dislocation interaction must be taken into account, in particular, for edge dislocations and dislocations inclined to the surface. Examples are given for dislocations on GaAs(110) and Pt(111) surfaces. By matching the REM images with the computed images the character of some dislocations has been identified.