| 1. |
- Atalaya, Juan, 1981, et al.
(författare)
-
Continuum elastic modeling of graphene resonators
- 2008
-
Ingår i: Nano Letters. - 1530-6992 .- 1530-6984. ; 8:12, s. 4196-4200
-
Tidskriftsartikel (refereegranskat)abstract
- Starting from an atomistic approach, we have derived a hierarchy of successively more simplified continuum elasticity descriptions for modeling the mechanical properties of suspended graphene sheets. We find that already for deflections of the order of 0.5 Å a theory that correctly accounts for nonlinearities is necessary and that for many purposes a set of coupled Duffing-type equations may be used to accurately describe the dynamics of graphene membranes. The descriptions are validated by applying them to square graphene-based resonators with clamped edges and studying numerically their mechanical responses. Both static and dynamic responses are treated, and we find good agreement with recent experimental findings.
|
|
| 2. |
- Axelsson, S., et al.
(författare)
-
Theoretical and experimental investigations of three-terminal carbon nanotube nanorelays
- 2005
-
Ingår i: New J. Phys. - : IOP Publishing. - 1367-2630. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- We present theoretical and experimental investigations of three-terminal nanoelectromechanical relays based on suspended carbon nanotubes. A charge is induced in the nanotube by applying a voltage to an underlying gate electrode thus inducing the nanotube to bend and make contact with a drain electrode. Such devices have potential applications as fast switches, logic devices, memory elements and pulse generators. We describe two modes of operation: a contact mode where the nanotube makes physical contact with the drain electrode and a non-contact mode where electrical contact between the nanotube and the drain electrode is made via a field emission current.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Eriksson, Anders, 1975, et al.
(författare)
-
Direct Transmission Detection of Tunable Mechanical Resonance in an Individual Carbon Nanofiber Relay
- 2008
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- A direct on-chip transmission measurement of the resonance frequency of an individual singly clamped carbon nanofiber relay is reported. The experimental results are in good agreement with a small signal model and show the expected tuning of the resonance frequency with changing bias voltage.
|
|
| 6. |
- Huldt, Caroline, 1976, et al.
(författare)
-
Electronic transport in a shuttle with a discrete energy spectrum
- 2009
-
Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 11, s. 013060-
-
Tidskriftsartikel (refereegranskat)abstract
- We present a multiscale approach for a molecular nanoelectromechanical shuttle, which takes into account the discrete energy levels and realistic orbitals of a specific molecular system. We deploy a Cu13 cluster as a central island and describe the electrodes within the jellium model. The shuttling features are then examined for a wide spectrum of bias voltages. The microscopic data of the cluster are obtained with density functional theory (DFT) while the macroscopic part combines stochastic charge dynamics, based on the microscopically evaluated tunnelling rates, with Newtonian dynamics. We find four transport regimes within the analysed bias voltage interval: a blocked regime (Vbias≤ 2 V), a pure shuttling regime (3 V ≤Vbias≤ 4 V), a mixed regime (5 V ≤Vbias≤ 6 V) and a direct tunnelling regime (Vbias≥7 V). In the two latter cases, the shuttling motion leads to a reduced current as compared to an island with a fixed position. The transport characteristics are strongly coupled to the availability of energetically allowed channels and the system therefore depends strongly on the microscopic details and bias voltages. For the setup at hand, however, the shuttling transport of one electron is ubiquitous and stable for all but the blocked regime.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Isacsson, Andreas, 1975, et al.
(författare)
-
Electronic superlattices in corrugated graphene
- 2008
-
Ingår i: Physical Review B. - 1098-0121. ; 77:3, s. 035423-
-
Tidskriftsartikel (refereegranskat)abstract
- We theoretically investigate electron transport through corrugated graphene ribbons and show how the ribbon curvature leads to an electronic superlattice with a period set by the corrugation wavelength. Transport through the ribbon depends sensitively on the superlattice band structure which, in turn, strongly depends on the geometry of the deformed sheet. In particular, we find that for ribbon widths where the transverse level separation is comparable to the band edge energy, a strong current switching occurs as a function of an applied back gate voltage. Thus, artificially corrugated graphene sheets or ribbons can be used for the study of Dirac fermions in periodic potentials. Furthermore, this provides an additional design degree of freedom for graphene-based electronics.
|
|
| 10. |
|
|
| 11. |
- Isacsson, Andreas, 1975, et al.
(författare)
-
Parametric resonances in electrostatically interacting carbon nanotube arrays
- 2009
-
Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 79:16, s. 165418-
-
Tidskriftsartikel (refereegranskat)abstract
- We study, numerically and analytically, a model of a one-dimensional array of carbon nanotube resonators in a two-terminal configuration. The system is brought into resonance upon application of an ac signal superimposed on a dc bias voltage. When the tubes in the array are close to each other, electrostatic interactions between tubes become important for the array dynamics. We show that both transverse and longitudinal parametric resonances can be excited in addition to primary resonances. The intertube electrostatic interactions couple modes in orthogonal directions and affect the mode stability.
|
|
| 12. |
|
|
| 13. |
|
|
| 14. |
|
|
| 15. |
- Lassagne, Benjamin, et al.
(författare)
-
Coupling Mechanics to Charge Transport in Carbon Nanotube Mechanical Resonators
- 2009
-
Ingår i: Science. - 0036-8075 .- 1095-9203. ; 325, s. 1107-1110
-
Tidskriftsartikel (refereegranskat)abstract
- Nanoelectromechanical resonators have potential applications in sensing, cooling, and mechanicalsignal processing. An important parameter in these systems is the strength of coupling the resonatormotion to charge transport through the device. We investigated the mechanical oscillations of asuspended single-walled carbon nanotube that also acts as a single-electron transistor. The couplingof the mechanical and the charge degrees of freedom is strikingly strong as well as widely tunable(the associated damping rate is ~3 MHz). In particular, the coupling is strong enough to drivethe oscillations in the nonlinear regime.
|
|
| 16. |
- Rehammar, Robert, 1980, et al.
(författare)
-
Nanowire-based tunable photonic crystals
- 2008
-
Ingår i: Optics Express. ; 16:26, s. 21682-21691
-
Tidskriftsartikel (refereegranskat)abstract
- Photonic crystals, materials with periodically varying refractive indices, show exciting optical properties that enable many technological applications. Conventional photonic crystals have optical properties that are determined at the time of fabrication and the ability to tune them is quite limited, particularly at visible frequencies. We investigate theoretically the possibility to use nanowires or nanotubes as the building block for tunable two-dimensional photonic crystals. Tunability is achieved by fabricating flexible nanowires in a periodic pattern and actuating them electrostatically. This changes the lattice basis, which in turn modifies the optical properties of the photonic crystal. We use a finite-difference time-domain method to model photonic crystals with changeable bases. We show that the optical transmission through a two-dimensional photonic crystal with only a few rows of nanowires in the light propagating direction can be electrostatically tuned from over 90% transmission to less than 10%. We demonstrate that tunability is maintained in realistic three-dimensional experimental geometries. Finally, we analyse the performance of the photonic crystals in terms of actuation voltages and tuning speeds, and conclude that the response time of a tunable carbon-nanofibre-based photonic crystal lies in the microsecond range.
|
|
| 17. |
- Samadikhah, Kaveh, 1982, et al.
(författare)
-
General elasticity theory for graphene membranes based on molecular dynamics
- 2007
-
Ingår i: Materials Research Society Symposium Proceedings. - 0272-9172. - 9781605608266 ; , s. 109-114
-
Konferensbidrag (refereegranskat)abstract
- We have studied the mechanical properties of suspended graphene membranes using molecular dynamics (MD) and generalized continuum elasticity theory (GE) in order to develop and assess a continuum description for graphene. The MD simulations are based on a valence force field model which is used to determine the deformation and the elastic energy of the membrane (EMD) as a function of external forces. For the continuum description, we use the expression Econt = Estretching + Ebending for the elastic energy functional. The elastic parameters (tensile rigidity and Poisson ratio) entering Econt are determined by requiring that E cont = EMD for a set of deformations. Comparisons with the MD results show excellent agreement. We find that the elastic energy of a supported graphene sheets is typically dominated by the nonlinear stretching terms whereas a linear description is valid only for very small deflections. This implies that in some applications, i.e. NEMS, a linear description is of limited applicability.
|
|
| 18. |
- Svensson, Johannes, 1978, et al.
(författare)
-
A carbon nanotube gated carbon nanotube transistor with 5 ps gate
- 2008
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 19
-
Tidskriftsartikel (refereegranskat)abstract
- Semiconducting carbon nanotubes (CNTs) are attractive as channel material for field-effect transistors due to their high carrier mobility. In this paper we show that a local CNT gate can provide a significant improvement in the subthreshold slope of a CNT transistor compared to back gate switching and provide gate delays as low as 5 ps. The CNT gated CNT transistor devices are fabricated using a two-step chemical vapour deposition technique. The measured transfer characteristics are in very good agreement with theoretical modelling results that provide confirmation of the operating principle of the transistors. Gate delays below 2 ps should be readily achievable by reducing the thickness of the gate dielectric.
|
|
| 19. |
|
|
| 20. |
|
|
| 21. |
|
|
| 22. |
- Viefers, Susanne, 1970, et al.
(författare)
-
Nanotube relay device
- 2007
-
Patent (övrigt vetenskapligt/konstnärligt)
|
|
