Self-affine roughness influence on the pull-in voltage in capacitive electromechanical devices

In this work we investigate the influence of self-affine roughness parameters on the pull-in voltage in capacitive microelectromechanical devices. The capacitor plate roughness is considered as self-affine type, which is described by the roughness amplitude w, the lateral correlation length ξ, and the roughness exponent H. By comparing the influence of the three parameters, we confirm that not only the long-wavelength roughness parameters w and ξ, but also the short-wavelength fine roughness details, as described by the roughness exponent H, play a major role. Therefore, the proper characterization of the involved surface roughness and its evolution at all relevant length scales are necessary to gauge properly the performance of associated devices.