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Advances in Condensed Matter Physics
Volume 2015, Article ID 453125, 8 pages
http://dx.doi.org/10.1155/2015/453125
Research Article

Ab Initio Study of Strain Effects on the Quasiparticle Bands and Effective Masses in Silicon

1Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
2Department Physik, Universität Paderborn, 33095 Paderborn, Germany

Received 1 December 2014; Accepted 16 January 2015

Academic Editor: Da-Ren Hang

Copyright © 2015 Mohammed Bouhassoune and Arno Schindlmayr. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Using ab initio computational methods, we study the structural and electronic properties of strained silicon, which has emerged as a promising technology to improve the performance of silicon-based metal-oxide-semiconductor field-effect transistors. In particular, higher electron mobilities are observed in n-doped samples with monoclinic strain along the [110] direction, and experimental evidence relates this to changes in the effective mass as well as the scattering rates. To assess the relative importance of these two factors, we combine density-functional theory in the local-density approximation with the approximation for the electronic self-energy and investigate the effect of uniaxial and biaxial strains along the [110] direction on the structural and electronic properties of Si. Longitudinal and transverse components of the electron effective mass as a function of the strain are derived from fits to the quasiparticle band structure and a diagonalization of the full effective-mass tensor. The changes in the effective masses and the energy splitting of the conduction-band valleys for uniaxial and biaxial strains as well as their impact on the electron mobility are analyzed. The self-energy corrections within lead to band gaps in excellent agreement with experimental measurements and slightly larger effective masses than in the local-density approximation.