Density Functional Modeling of Defects and Impurities in Silicon Materials

Abstract

This is a contribution targeted for early scientists, from both academia and industry, providing the grounds for defect modeling in silicon materials using density functional methods. It starts with a revision of the theoretical framework and tools, including relevant approximations such as the treatment of the exchange-correlation interactions and the use of pseudopotentials. It then describes how to step up from total energies, electron densities and Kohn-Sham states to the actual defect observables. Particular emphasis is given to the calculation of spectroscopic observables such as electrical levels, local vibrational modes, spin densities, migration barriers, and defect response to uniaxial stress. Each of these techniques is accompanied by examples of defect calculations. It is shown how these results can be crucial in unraveling a detailed picture of many complexes, including substitutional and interstitial impurities, dopants, transition metals, carbon, oxygen or hydrogen. In the last section we take a look at some developments in modeling defects in silicon nanostructures. While holding promising optical and magnetic properties, nano-silicon presents many challenges, particularly with regard to defect control, doping and electrical transport.