Probing thermal expansion of graphene and modal dispersion at low-temperature using graphene NEMS resonators

Abstract

We use suspended graphene electromechanical resonators to study the variation of resonant frequency as a function of temperature. Measuring the change in frequency resulting from a change in tension, from 300 K to 30 K, allows us to extract information about the thermal expansion of monolayer graphene as a function of temperature, which is critical for strain engineering applications. We find that thermal expansion of graphene is negative for all temperatures between 300K and 30K. We also study the dispersion, the variation of resonant frequency with DC gate voltage, of the electromechanical modes and find considerable tunability of resonant frequency, desirable for applications like mass sensing and RF signal processing at room temperature. With lowering of temperature, we find that the positively dispersing electromechanical modes evolve to negatively dispersing ones. We quantitatively explain this crossover and discuss optimal electromechanical properties that are desirable for temperature compensated sensors.

Dielectric‐Screening Reduction‐Induced Large Transport Gap in Suspended Sub‐10 nm Graphene Nanoribbon Functional Devices

“…We will discuss details in four monolayer CVD graphene–based devices (devices A–D) with milled constrictions prepared in exactly the same manner but inevitably with an uncontrolled orientations relative to the graphene crystallographic orientation. GNRs prepared by the described method are very stable at high (up to 550 K) and low temperatures (down to 150 K) even though the compressive stress of the electrodes at temperatures lower than 300 K induces tensile stress to the GNRs . This confirms the stability and reliability of the HIB milling approach and the obtained devices.…”

Radio frequency electrical transduction of graphene mechanical resonators

“…In this device, the dispersion is negative . In general, both positive dispersion (due to tensioning of the graphene membrane) and negative dispersion (due to a voltage-induced decrease in the effective spring constant) can be observed 14,18 . Fig.…”

Vibrational modes of ultrathin carbon nanomembrane mechanical resonators

“…7,8 Understanding the mechanical motion of a NM in the regime of nanoscale thickness is of fundamental importance and also essential for potential applications in the NEMS as building blocks. Recently, graphenebased NEMS have been intensively studied [9][10][11] and their use in optomechanics 12 and signal processing 13 have also been demonstrated. MoS 2 mechanical resonators have been investigated experimentally and the transition from the "plate" to the "membrane" regime was identified as the number of layers decreases.…”