Effects of a cloud of impurity atoms near a dislocation on electron microscopic contrast

Abstract

A model is proposed for the impurity‐atom cloud formed near an edge dislocation lying parallel to the surface taking into account the basic physical features of the real cloud. On the basis of the regularities obtained for the distribution of the displacement fields of the present model the eatures of the electron‐microscopy images are studied theoretically for a dislocation with a cloud. The presence of the cloud leads to a decrease of the edge intensity of the dislocation image independent of its bedding depth and to a change of the contrast sign at some depths. The diffraction conditions are found where these effects are mostly marked.

The influence of impurities on the dislocation splitting in semiconductors

“…where aiy(r) are the stresses induced by the atmosphere around the first dislocation a t the location of the second dislocation, a&(r) can be represented, in accordance with the present model, by two terms [14],…”

“…The presence of these atmospheres decreases the elastic stresses caused by dislocations with edge components of the Burgers vector and does not change the stresses caused by the screw components. For simplicity, the Cottrell atmosphere can be represented by two components: a) the dipole redistribution of PDs in the dislocation field and b) the dilatation cylinder formed by the redundant atoms flowing t o the vicinity of the dislocation core from the surrounding material [14]. Consider the force Fa (Fig.…”

A TEM study of the interaction of sub-threshold electron beam induced defects in II–VI compounds

“…The nature of the dipole structure was confirmed by observation of the change in image spacing on reversing the diffraction vector g. Dipoles usually form by dislocation climb through the absorption or emission of point defects, and similar defects have been observed in 100 keV electron beam irradiated ZnSe [6] and HVEM irradiated Si [lo]. Diffraction contrast similar to a Cottrell cloud structure [12] is also apparent around the dislocation shown in Fig. 2b.…”

The effect of the crystal anisotropy on the energy of the dislocation-impurity atmosphere elastic interaction in silicon

“…The very fact that these phenomena do exist was interpreted as an evidence for the presence of atmospheres near dislocations. The possibility, in principle, to detect the atmospheres by means of the electron microscopy technique was shown in [4] making the assumption of a purely elastic interaction between the atmosphere and a dislocation.…”