Mystery of current spike: Nanoscale plasticity revisited

Abstract

This paper addresses the current spike (CS) phenomenon revealed by in situ measurements of electrical response during nanoindentation. The CS is defined as the sharp initial increase in electric current through the highly compressed GaAs/metallic indenter nanocontact and its decay to zero upon termination of elastic deformation. The clarification of this new effect is justified by our ab initio analysis of the metal/semiconductor contact. The obtained results reveal the common origin of the simultaneous mechanical and electrical responses, these being the pop-in event and the CS respectively. This leads to a substantial revision of our understanding of the onset of nanoscale plasticity. Our results support the hypothesis, deduced from atomistic simulations, of the non-dislocation incipient plasticity of GaAs. They are also in accord with the fresh idea of nanoscale deconfinement driven deformation of compressed silicon nanospheres.