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▲ [13a-A401-1] Effect of suspended electrodes on the dynamics of Graphene nano-resonators
Keywords:Nanomechanical resonator, Finite element analysis
Nanoscale mechanical resonators are candidates for ultra-sensitive sensing applications1 of vital physical quantities, such as, mass, force, charge, etc. It is further advantageous to fabricate nanoscale resonators from ultra-thin materials to achieve high-resolution sensing, due to their small effective mass. Graphene, a stable, atomically-thin 2D carbon material (along with its exceptional mechanical properties) is therefore an excellent choice for fabricating nanoscale resonator2,3. Typically, a suspended graphene nano-ribbon is vibrated in its fundamental frequency (f) by a periodic mechanical excitation (Fig. 1(A)); shift in this frequency (δf) under the influence of an external perturbation, like addition of mass by gas adsorption, is then used to measure the extent of that perturbation, facilitating the sensing process4.
A common way to suspend graphene nano-ribbon (GNR; produced by mechanical exfoliation or reactive etching of CVD graphene film on SiO2/Si substrates) is by (bHF) etching of the oxide layer underneath the GNR5,6. This process often undercuts the metal-electrodes5,6 on the GNR-resonator, partially suspending them along with the GNR-resonator (Fig. 1(A)); however, the influence of the suspended electrodes on the eigenmodes and the dynamics of the GNR-resonators is unknown. Using finite element simulation (Comsol Multiphysics), we analyze the eigenmodes of GNR-resonators with suspended metal (Au) electrodes. We show the role of the suspended metal electrodes in determining the mode-shapes and the eigen-frequencies of such GNR-resonators (Fig. 1(B)).
A common way to suspend graphene nano-ribbon (GNR; produced by mechanical exfoliation or reactive etching of CVD graphene film on SiO2/Si substrates) is by (bHF) etching of the oxide layer underneath the GNR5,6. This process often undercuts the metal-electrodes5,6 on the GNR-resonator, partially suspending them along with the GNR-resonator (Fig. 1(A)); however, the influence of the suspended electrodes on the eigenmodes and the dynamics of the GNR-resonators is unknown. Using finite element simulation (Comsol Multiphysics), we analyze the eigenmodes of GNR-resonators with suspended metal (Au) electrodes. We show the role of the suspended metal electrodes in determining the mode-shapes and the eigen-frequencies of such GNR-resonators (Fig. 1(B)).