title: Graphene as a Massless Electrode for Ultrahigh-Frequency Piezoelectric Nanoelectromechanical Systems.
abstract: Designing "ideal electrodes" that simultaneously guarantee low mechanical damping and electrical loss as well as high electromechanical coupling in ultralow-volume piezoelectric nanomechanical structures can be considered to be a key challenge in the NEMS field. We show that mechanically transferred graphene, floating at van der Waals proximity, closely mimics "ideal electrodes" for ultrahigh frequency (0.2 GHz < f0 < 2.6 GHz) piezoelectric nanoelectromechanical resonators with negligible mechanical mass and interfacial strain and perfect radio frequency electric field confinement. These unique attributes enable graphene-electrode-based piezoelectric nanoelectromechanical resonators to operate at their theoretically "unloaded" frequency-limits with significantly improved electromechanical performance compared to metal-electrode counterparts, despite their reduced volumes. This represents a spectacular trend inversion in the scaling of piezoelectric electromechanical resonators, opening up new possibilities for the implementation of nanoelectromechanical systems with unprecedented performance.
authors.affiliation: †Department of Electrical and Computer Engineering and ‡Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States.
authors.forename: Zhenyun
authors.initials: Z
authors.lastname: Qian
authors.affiliation: †Department of Electrical and Computer Engineering and ‡Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States.
authors.forename: Fangze
authors.initials: F
authors.lastname: Liu
authors.affiliation: †Department of Electrical and Computer Engineering and ‡Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States.
authors.forename: Yu
authors.initials: Y
authors.lastname: Hui
authors.affiliation: †Department of Electrical and Computer Engineering and ‡Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States.
authors.forename: Swastik
authors.initials: S
authors.lastname: Kar
authors.affiliation: †Department of Electrical and Computer Engineering and ‡Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States.
authors.forename: Matteo
authors.initials: M
authors.lastname: Rinaldi
keywords: Graphene; NEMS; aluminum nitride; massless electrode; piezoelectric