Physical models for coupled electromechanical analysis of silicon nanoelectromechanical systems

Nanoelectromechanical systems (NEMS) can be designed and characterized by understanding the interaction and coupling between the mechanical, electrical, and the van der Waals energy domains. In this paper, we present physical models and their numerical simulation for coupled electrical and mechanical analysis of silicon NEMS. A nonlinear continuum elastic model is employed for mechanical analysis. The material properties required in the continuum model are extracted from molecular-dynamics simulations. We present three electrostatic models—namely, the classical conductor model, the semiclassical model, and the quantum-mechanical model, for electrostatic analysis of NEMS at various length scales. The electrostatic models also account for the corrections to the energy gap and the effective mass due to the strain in the silicon nanostructure. A continuum layer approach is introduced to compute the van der Waals forces. The coupling between the mechanical, electrical, and the van der Waals energy domains as well as their numerical implementation is described. Numerical results are presented for several silicon NEM switches to understand the static electromechanical pull-in behavior.