High, Size-Dependent Quality Factor in an Array of Graphene Mechanical Resonators

Abstract

Graphene's unparalleled strength, stiffness, and low mass per unit area make it an ideal material for nanomechanical resonators, but its relatively low quality factor is an important drawback that has been difficult to overcome. Here, we use a simple procedure to fabricate circular mechanical resonators of various diameters from graphene grown by chemical vapor deposition. In addition to highly reproducible resonance frequencies and mode shapes, we observe a striking improvement of the membrane quality factor with increasing size. At room temperature, we observe quality factors as high as 2400 ± 300 for a resonator 22.5 μm in diameter, about an order of magnitude greater than previously observed quality factors for monolayer graphene. Measurements of quality factor as a function of modal frequency reveal little dependence of Q on frequency. These measurements shed light on the mechanisms behind dissipation in monolayer graphene resonators and demonstrate that the quality factor of graphene resonators relative to their thickness is among the highest of any mechanical resonator demonstrated to date.

Approaching intrinsic performance in ultra-thin silicon nitride drum resonators

“…The highest achievable quality factors for ultrathin silicon nitride membranes scales linearly with the diameter, a dependence also seen in self tensioned graphene drums. 19 We observe a weak thickness dependent Q À1 floor for these membrane resonators, resulting in a higher RQ product for thinner membranes. This indicates that two dimensional materials like graphene 19 and ultrathin silicon nitride (this study) can achieve high quality factors by an appropriate combination of tensile stress, size, and mode of the resonators enabling the use of such devices for optomechanical experiments and resonant sensors.…”

“…6. Thickness dependence of quality factors of different resonators studied in the literature 2,6,10,19 compared to the resonators measured for this study displaying the highest Q's measured for a given thickness (red squares). These show an increase in Q with reduced thickness (i.e., surface to volume ratio, R) indicating that ultrathin silicon nitride resonators can achieve high quality factors with an appropriate combination of tensile stress, size, and modes of the resonators.…”

“…9,10 As the membranes are thinned, the increased surface to volume ratio (R) results in dissipation mechanisms that are primarily related to stress assisted relaxation of defects, dangling bonds or contamination at the surface. To illustrate how distinctly the resonators described in this paper behave when compared to previously investigated structures, we examine in Figure 6 the volume to surface ratio ($t) versus Q of various resonators made from different materials 4,9,10,19 and tensioned silicon nitride membranes of different thickness. The high stress silicon nitride membranes, show very high Q for very high surface to volume ratio (R), with the highest measured Q increasing as the thickness is reduced, contrary to the trend observed in other systems.…”

High quality single crystal Ge nano-membranes for opto-electronic integrated circuitry

“…Single and double walled carbon nanotube (CNT) resonators have Q factors of 40-200, 47 while multi-walled CNTs and CNT fibers reported Q factors reach 250-2500. [48][49][50][51] Graphene resonators exhibit slightly higher Q factors from several hundred [52][53][54] to over a thousand, 55,56 while graphene oxide has even higher Q factor of 4000. 57 Recently, Q factors as high as 10 5 were demonstrated for graphene membranes.…”

Colorimetry Technique for Scalable Characterization of Suspended Graphene

“…12,13 Single-layer graphene (SLG) drums have been extensively studied, showing unique mechanical properties. [14][15][16][17][18] Many groups have demonstrated the scalability of CVD SLG drums and analyzed the statistical variation of their mechanical properties by measuring several drums with laser interferometry, 19,20 Raman spectroscopy, 12,21,22 and atomic force microscopy. 23,24 However, any attempt to commercialize graphene mechanical sensors is ineffective unless a characterization technique that is parallel, contactless, and affordable at the same time becomes available.…”