Silicon Nanowires: From Empirical to First Principles Modeling

Abstract:

Silicon nanowires have been the subject of intense investigation over the last decade. The experimental realization of nanowire configurations with a wide range of diameters, lengths, and surface types leads us to envision a wealth of applications, running from selective sensors of rapid response to electronic devices. In this period, theoretical modeling has helped to understand the electronic, mechanical, optical and transport properties of nanowires and to explore applications of such properties in the context of the current electronic technologies. These modern theoretical calculations have reached a point where realistic description of materials properties are provided by computational simulations. Carefully constructed empirical potentials provide a good description of silicon-nanowire energetics, making possible investigations of the stability of silicon wires with different surface terminations (or facets) for a given family of nanowires. Simulations using empirical potentials have also been employed to examine the thermal and mechanical stability of silicon nanowires, and also the response under external load. In the latter case, there is and indication that the response under load of silicon nanowires is different from the bulk, to the extent that crack propagation is suppressed and healing at the crack is mediated by surface effects. Investigation of nanowire properties are also within the reach of tight-binding and first principles methodologies, that have been used to examine the effects of quantum confinement on the nanowire electronic, transport and structural properties, as well as the nature of their surface states. These methods have also been used to examine the possibility of structural transitions of very thin silicon wires, induced by surface effects