An Exploration of the Electromechanical Response of Suspended Graphene and Its Applications
- Author(s): Ng, Jimmy
- Advisor(s): xie, ya-hong
- et al.
Graphene is a 2D sheet of carbon atoms arranged in a hexagonal lattice whose unique structure gives rise to extraordinary mechanical and electronic properties. For these reasons, suspended graphene structures have potential applications in micro-electromechanical systems (MEMS). This dissertation serves as an exposition exploring the electromechanical response of suspended graphene and its applications in MEMS. After a thorough introduction to graphene is provided, the dissertation presents a series of studies. First, a suspended graphene ribbon device was studied as a mechanical switch used to provide electrostatic discharge protection tosemiconductor integrated circuits, establishing proof of concept via standard electrostatic discharge industry testing. Second, the effect of polymer residue from device fabrication processes on the electromechanical response of suspended graphene was investigated. After rigorous study using innovative compliant mechanisms, polymer residue was found to have two prominent effects on suspended graphene: 1) a variation polymer residue thickness led to a variation in end device parameters such as the pull-in voltage and 2) the polymer residue itself supports the suspension of graphene by increasing the rigidity of the suspended structure. These results have implications to the manufacturability and reliability of suspended graphene MEMS devices. Finally, a theoretical study modeling the suspended graphene ribbon device was conducted for a separate application: a resonator for high frequency power conversion, an idea that was made attractive again by the extraordinary material properties of graphene. In this study, the device design, electromechanical modeling, and results relevant to high frequency power conversion applications are presented and discussed. The results indicate that a suspended graphene ribbon resonator can generate oscillation frequencies within the THz gap when the graphene sheet itself approaches sufficiently small dimensions; however, there also exists a tradeoff between the power generated and the signal quality which must be taken into account when designing these resonators. In all the studies presented, the device design, experimental procedures, algorithms for computer modeling, etc. are explained in detail. Lastly, standard semiconductor industry fabrication and characterization techniques were primarily used in doing this work, imbuing the potential for industrial large-scale adoption in the future.