Strain-Induced, Off-Diagonal, Same-Atom Parameters in Empirical Tight-Binding Theory Suitable for [110] Uniaxial Strain Applied to a Silicon Parametrization

Timothy B. Boykin, The University of Alabama, Huntsville
Mathieu Luisier, Network for Computational Nanotechnology, Purdue University
Mehdi Salmani-Jelodar, Network for Computational Nanotechnology, Purdue University
Gerhard Klimeck, Network for Computational Nanotechnology, Purdue University

Date of this Version



Phys. Rev. B 81, 125202 (2010)

This document has been peer-reviewed.



State-of-the-art transistors achieve their improved performance through strain engineering. The somewhat unusual uniaxial [110] strain is of particular importance as it provides a significant mobility increase for electrons. Empirical tight binding has shown tremendous benefits in modeling realistically large structures including standard strain conditions, but often fails to predict the correct uniaxial [110] strain behavior because most treatments neglect the same-atom different-orbital matrix elements induced by this strain. Two separate mechanisms are responsible for these conditions: Loumlwdin orbital changes and displacement of nearest-neighbor potentials. We present a model which separately includes both mechanisms via parameters whose range of validity can be independently determined. Using this method we optimize a set of strain parameters for Si. The combination of both effects is able to reproduce the Si X-z-valley transverse mass splitting under uniaxial [110] strain. We then use this model to calculate the drain current of a strained double-gate, ultrathin-body metal-oxide-semiconductor field-effect transistor, finding experimentally plausible results.


Engineering | Nanoscience and Nanotechnology