13 research outputs found
Dissipation in graphene and nanotube resonators
Different damping mechanisms in graphene nanoresonators are studied: charges
in the substrate, ohmic losses in the substrate and the graphene sheet,
breaking and healing of surface bonds (Velcro effect), two level systems,
attachment losses, and thermoelastic losses. We find that, for realistic
structures and contrary to semiconductor resonators, dissipation is dominated
by ohmic losses in the graphene layer and metallic gate. An extension of this
study to carbon nanotube-based resonators is presented.Comment: Published version with updated reference
Surface dissipation in nanoelectromechanical systems: Unified description with the standard tunneling model and effects of metallic electrodes
By modifying and extending recent ideas [C. Seoanez et al., Europhys. Lett.
78, 60002 (2007)], a theoretical framework to describe dissipation processes in
the surfaces of vibrating micro- and nanoelectromechanical devices, thought to
be the main source of friction at low temperatures, is presented. Quality
factors as well as frequency shifts of flexural and torsional modes in doubly
clamped beams and cantilevers are given, showing the scaling with dimensions,
temperature, and other relevant parameters of these systems. Full agreement
with experimental observations is not obtained, leading to a discussion of
limitations and possible modifications of the scheme to reach a quantitative
fitting to experiments. For nanoelectromechanical systems covered with metallic
electrodes, the friction due to electrostatic interaction between the flowing
electrons and static charges in the device and substrate is also studied.Comment: 17 pages, 7 figure
Electrostatic interactions between graphene layers and their environment
We analyze the electrostatic interactions between a single graphene layer and
a SiO susbtrate, and other materials which may exist in its environment. We
obtain that the leading effects arise from the polar modes at the SiO
surface, and water molecules, which may form layers between the graphene sheet
and the substrate. The strength of the interactions implies that graphene is
pinned to the substrate at distances greater than a few lattice spacings. The
implications for graphene nanoelectromechanical systems, and for the
interaction between graphene and a STM tip are also considered.Comment: improved introduction, section on suspended graphene correcte
Minimization of phonon-tunneling dissipation in mechanical resonators
Micro- and nanoscale mechanical resonators have recently emerged as
ubiquitous devices for use in advanced technological applications, for example
in mobile communications and inertial sensors, and as novel tools for
fundamental scientific endeavors. Their performance is in many cases limited by
the deleterious effects of mechanical damping. Here, we report a significant
advancement towards understanding and controlling support-induced losses in
generic mechanical resonators. We begin by introducing an efficient numerical
solver, based on the "phonon-tunneling" approach, capable of predicting the
design-limited damping of high-quality mechanical resonators. Further, through
careful device engineering, we isolate support-induced losses and perform the
first rigorous experimental test of the strong geometric dependence of this
loss mechanism. Our results are in excellent agreement with theory,
demonstrating the predictive power of our approach. In combination with recent
progress on complementary dissipation mechanisms, our phonon-tunneling solver
represents a major step towards accurate prediction of the mechanical quality
factor.Comment: 12 pages, 4 figure
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Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201