A pile-up of edge dislocations to relax Misfit strain

Soufi, Aziz; Aitoubba, Ayoub; El-hami, Khalil; Talea, Mohamed; Bakali, Assia; Grilhé, Jean

Journal of Materials and Engineering Structures
Volume 4, Numéro 1, Pages 11-23
2017-03-31

A Pile-up Of Edge Dislocations To Relax Misfit Strain

Authors : Soufi Aziz . Aitoubba Ayoub . El-hami Khalil . Talea Mohamed . Bakali Assia . Grilhé Jean .

Abstract

It is shown that very large stresses may be present in the thin films that comprise integrated circuits and magnetic disks and that these stresses can cause deformation and fracture of the material. For a crystalline film on a non-deformable substrate, a key problem involves the movement of dislocations in the thin film. An analysis of this problem provides insight into both the formation of misfit dislocations in epitaxial thin films and the high strengths of thin metal films on substrates. We develop in this paper, theoretical calculations for dislocation nucleation phenomena in nanomaterials obtained by hetero-epitaxial growth of thin films on substrates having lattice mismatch defects. Atomic force microscopy observations showed the nucleation of dislocations from free lateral surfaces to relax the "misfit" strain, here we explain the principle of nucleating edge dislocations from these surfaces by the theoretical calculation, using the method of image stress and energy study. We begin, by treating the case of a single dislocation and then generalize the work at a pile-up of n interface dislocations.