Calculation of pull-in voltages for carbon-nanotube-based nanoelectromechanical switches

We study the pull-in voltage characteristics of several nanotube electromechanical switches, such as double-wall carbon nanotubes suspended over a graphitic ground electrode. We propose parametrized continuum models for three coupled energy domains: the elastostatic energy domain, the electrostatic energy domain and the van der Waals energy domain. We compare the accuracy of the continuum models with atomistic simulations. Numerical simulations based on continuum models closely match the experimental data reported for carbon-nanotube-based nanotweezers. An analytical expression, based on a lumped model, is derived to compute the pull-in voltage of cantilever and fixed-fixed switches. We investigate the significance of van der Waals interactions in the design of nanoelectromechanical switches.