In order to reproduce the high stress conditions reached in nanostructures, two experimental techniques have been used: high-pressure deformation on bulk materials and plastic deformation of micro and nano pillars. Transmission Electron Microscopy (TEM) has been conducted on deformation microstructures in order to analyze dislocation core structures. Concurrently the nucleation of dislocations has been studied in various conditions of stress and temperature by using atomistic simulations.

 This paper aims at reviewing the effect of stress and size on the dislocation nucleation in semi conductor materials. Results on silicon will be presented. Both simulations and TEM observations converge in showing that in silicon dislocation core configurations have different nature depending on the temperature and nucleation stress [1]: perfect dislocations are found to be nucleated at high stress as compared to dissociated dislocations at moderate stress. The properties of such core structures will be discussed. Although most of the experiments and simulations are relevant to silicon, this behavior is common to a number of semiconductor materials. Indeed this impacts also silicon carbide [2] in which stresses usually favor polytypes formation whereas perfect dislocations nucleated at very high stresses do not contribute to any phase transformations.

[1] Rabier J, Pizzagalli L and Demenet J L 2010, Elsevier B.V. Dislocations in Solids, Edited by J.P. Hirth and L. Kubin (North-Holland, Amsterdam), 93, 47

[2] Demenet J L, Amer M, Tromas C, Eyidi D and J. Rabier J 2013, pssc 10, 64

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1. Study of dislocation nucleation activation from surface step by atomistic calculations