Interrogating contact-mode silicon carbide (SiC) nanoelectromechanical switching dynamics by ultrasensitive laser interferometry

Abstract

We report on initial experimental demonstration of probing the dynamics of nanoscale contacts in robust nanoelectromechanical switches based on silicon carbide (SiC) nanocantilevers. For the first time, we measure the dynamical behavior of contact-mode SiC nanoscale electromechanical switches by directly probing the vibrating tips of the SiC nanocantilevers, using ultrasensitive laser interferometric techniques. First, we devise a novel `pump-and-probe'-type optical technique in which we use an RF-modulated 405nm (blue) laser to excite the SiC cantilevers, while using a 633nm (red) laser interferometer to probe the dynamics of their tips. Second, we directly actuate the SiC devices via their electrostatic gates, while monitoring the cantilevers' motions optically. By actuating the SiC cantilever switches near resonance with increasing amplitudes, we reveal new characteristics in motion dynamics when the devices are making contacts periodically. We demonstrate milli-Volt actuated SiC NEMS with cantilever tips tapping on the contact electrodes periodically, for >10 billion cycles (in `cold' switching mode).