Influence of surface effects on the pull-in instability of NEMS electrostatic switches

Abstract

The influence of surface effects, including residual surface stress and surface elasticity, onthe pull-in instability of electrostatic switches in nanoelectromechanical systems (NEMS) isstudied using an Euler–Bernoulli beam model. This model is inherently nonlinear due tothe driving electrostatic force and Casimir force which become dominant at the nanoscale.Since no exact solutions are available for the resulting nonlinear differential equation, He’shomotopy perturbation method (HPM) is used to get the approximate analyticalsolutions to the static bending of NEMS switches, which are validated by numericalsolutions of the finite difference method (FDM). The results demonstrate that surfaceeffects play a significant role in the selection of basic design parameters of NEMSswitches, such as static deflection, pull-in voltage and detachment length. Surfaceeffects on low-voltage actuation windows are also characterized for these switches.The present study is envisaged to provide useful insights for the design of NEMSswitches.