Micromachines, Vol. 7, Pages 158: Energy Dissipation in Graphene Mechanical Resonators with and without Free Edges

Graphene-based nanoelectromechanical systems (NEMS) have high future potential to realize sensitive mass and force sensors owing to graphene's low mass density and exceptional mechanical properties. One of the important remaining issues in this field is how to achieve mechanical resonators with a high quality factor (Q). Energy dissipation in resonators decreases Q, and suppressing it is the key to realizing sensitive sensors. In this article, we review our recent work on energy dissipation in doubly-clamped and circular drumhead graphene resonators. We examined the temperature (T) dependence of the inverse of a quality factor ( Q - 1 ) to reveal what the dominant dissipation mechanism is. Our doubly-clamped trilayer resonators show a characteristic Q - 1 -T curve similar to that observed in monolayer resonators: Q - 1 ∝ T 2 above ∼100 K and ∝ T 0.3 below ∼100 K. By comparing our results with previous experimental and theoretical results, we determine that the T 2 and T 0.3 dependences can be attributed to tensile strain induced by clamping metals and vibrations at the free edges in doubly-clamped resonators, respectively. The Q - 1 -T curve in our circular drumhead resonators indicates that removing free edges and clamping metal suppresses energy dissipation in the resonators, resulting in a linear T dependence of Q - 1 in a wide temperature range.

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