Bulletin of the American Physical Society
APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013; Baltimore, Maryland
Session N7: Focus Session: Graphene Devices VIII |
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Sponsoring Units: DMP Chair: Frank Koppens, ICFO Barcelona Room: 303 |
Wednesday, March 20, 2013 11:15AM - 11:51AM |
N7.00001: Mechanical resonators based on nanotubes and graphene Invited Speaker: Adrian Bachtold Carbon nanotubes and graphene offer unique scientific and technological opportunities as nanoelectromechanical systems (NEMS). Namely, they have allowed the fabrication of mechanical resonators that can be operable at ultra-high frequencies and that can be employed as ultra-sensitive sensors of mass and charge. In addition, nanotubes and graphene have exceptional electron transport properties, including ballistic conduction over long distances. Coupling the mechanical motion to electron transport in these remarkable materials is thus highly appealing. Here, I will review some of our recent results on nanotube and graphene NEMSs, including the control of the mechanical oscillation using Coulomb blockade and mass sensing at the proton mass level. [Preview Abstract] |
Wednesday, March 20, 2013 11:51AM - 12:03PM |
N7.00002: Graphene on silicon nitride resonators for optomechanics Roberto De Alba, Vivek Adiga, Isaac Storch, Patrick Yu, Rob Ilic, Robert Barton, Sunwoo Lee, James Hone, Paul McEuen, Harold Craighead, Jeevak Parpia Recently, much work on nanoelectromechanical resonators has focused on high Q systems and on coherent back action used to suppress or enhance device motion. Here we attempt to merge these concepts by studying graphene on silicon nitride bilayer membranes. The high Q's of these hetero-structures, along with the conductivity of graphene, result in both electrostatic and optical tunability of mechanical resonance. By coupling these devices with a movable, highly reflective mirror to form a Fabry-Perot cavity, we are able to modulate resonator frequency and damping through cavity detuning. We thus present evidence of photothermal back action in these devices due to energy absorption from an impinging laser beam. We utilize both optical and electrical read-out schemes to detect device motion, enabling us to compare electrical and optical nonlinearities as a function of cavity detuning and capacitive drive. [Preview Abstract] |
Wednesday, March 20, 2013 12:03PM - 12:15PM |
N7.00003: Self-sustained graphene mechanical oscillators Changyao Chen, Sunwoo Lee, Vikram Deshpande, Philip Kim, James Hone Graphene poses excellent electrical and mechanical properties, therefore it is the most promising candidate for NanoElectroMechanical Systems. Recent developments of its CVD synthesis and fabrications makes the large scale integration for Radio Frequency (RF) applications possible. In this talk, I will present the structure and characteristics of self-sustained graphene mechanical oscillators, discuss the frequency tuning, and their phase noise performance, as well as low temperature behaviors. The demonstrated voltage controlled oscillators made from graphene pave the pathway for next generation on-chip integration of RF NEMS front-end. [Preview Abstract] |
Wednesday, March 20, 2013 12:15PM - 12:27PM |
N7.00004: Adiabatic Electron Pumping through Graphene-based Nanoelectromechanical Resonators Caio Lewenkopf, Alexander Croy We theoretically investigate the adiabatic electronic transport through graphene-based nanoelectromechanical resonators. The device is modeled by an effective long-wavelength Hamiltonian (given by the Dirac equation) for the electrons and using the continuum elastic theory for the mechanical motion. One obtains the equations of motion describing the system dynamics employing a non-equilibrium Green's function theory. Due to the mutual coupling between the electronic and mechanical degrees of freedom, both sets of equations have to be solved self-consistently. We present analytical and numerical results of the pumped charge and the mechanical response for a typical resonator setup. We also discuss the role of non-adiabatic corrections and the resulting damping of the mechanical motion. [Preview Abstract] |
Wednesday, March 20, 2013 12:27PM - 12:39PM |
N7.00005: Fabrication and Detection of Graphene Nano-Mechanical Oscillators Shonali Dhingra, Jen-Feng Hsu, Brian D'Urso Graphene's exceptionally high crystal and electronic quality, combined with being only one-atom thick, make it quite a sought-after material for nano-mechanics, sensing and electronics. We fabricate and characterize Nano-Mechanical Oscillators (NMO) from large-domain single-layer graphene grown with Chemical Vapor Deposition (CVD) on $\sim$2mm thick copper discs. The graphene is transferred from copper using Poly (methyl methacrylate) (PMMA), onto indigenous substrates customized for enhanced graphene adhesion and assistance in its optical detection. It is patterned into devices of different geometrical shapes, such as doubly clamped beams, circular drums and rectangular drums, using deep-UV lithography of PMMA, either before or after transfer. The phase and frequency response of the resonant motion of the NMO is monitored, which is electrically actuated and optically detected using interferometric techniques. These oscillators would be used as building blocks for hybrid quantum systems which couple classical oscillators with a quantum spin system. [Preview Abstract] |
Wednesday, March 20, 2013 12:39PM - 12:51PM |
N7.00006: Transfer-Free, Wafer-Scale Manufacturing of Graphene-Based Electromechanical Resonant Devices Michael Cullinan, Jason Gorman Nanoelectromechanical (NEMS) resonators offer the potential to extend the limits of force and mass detection due to their small size, high natural frequencies and high Q-factors. Graphene-based NEMS resonators are particularly promising due to their high elastic modulus and atomic thickness. However, widespread use of graphene in such systems is limited by the way in which graphene-based devices are typically fabricated. Most graphene-based NEMS devices are fabricated in a ``one-off'' manner using slow, limited scale methods such as mechanical exfoliation, electron beam lithography, or transfer from copper foils which can't be incorporated into standard micro/nanofabrication lines. This talk will present a method that can be used to manufacture graphene-based NEMS devices at the wafer scale using conventional microfabrication techniques. In this method graphene is grown directly on thin film copper using chemical vapor deposition. The copper film is then patterned and etched to produce graphene-based NEMS resonators. This talk will also address some of the challenges in fabricating a large number of graphene devices at the wafer scale including achieving high uniformity across the wafer, increasing device-to-device repeatability, and producing high device yields. [Preview Abstract] |
Wednesday, March 20, 2013 12:51PM - 1:03PM |
N7.00007: Manipulating Graphene Alexander Ruyack, Melina Blees, Samantha Roberts, Chris Martin, Arthur Barnard, Paul L. McEuen Graphene is both strong and flexible, making it a promising material for nanoscale hinges and other three-dimensional structures. Using sacrificial layers and surfactants, we are able to demonstrate control over the adhesion of monolayer graphene to a substrate. By patterning gold on the surface of the graphene, we created arrays of rigid pads bridged by graphene strips that can be decoupled from the surface in an aqueous environment. The pads allow us to manipulate the graphene both on and off the surface using lasers or micromanipulators. Our methods yield fundamental material data on graphene such as the macroscopic bending stiffness, and demonstrate the feasibility of a graphene hinge. We are currently exploring the use of magnetic control as a method for applying forces to stretch and fold graphene. We have already created micron-sized permanent magnets made of iron and successfully released them from the substrate, and are now integrating them into graphene devices. [Preview Abstract] |
Wednesday, March 20, 2013 1:03PM - 1:15PM |
N7.00008: Graphene Membrane Mechanics Qin Zhou, A. Zettl Graphene has extremely low mass density and high mechanical strength, useful qualities for mechanically vibrating systems. Here we report on construction and testing of graphene-based vibrating drumheads. We explore frequency response and damping characteristics, and energy transduction. [Preview Abstract] |
Wednesday, March 20, 2013 1:15PM - 1:27PM |
N7.00009: Measuring graphene's bending stiffness Melina Blees, Arthur Barnard, Samantha Roberts, Joshua W. Kevek, Alexander Ruyack, Jenna Wardini, Peijie Ong, Aliaksandr Zaretski, Siping Wang, Paul L. McEuen Graphene's unusual combination of in-plane strength and out-of-plane flexibility makes it promising for mechanical applications. A key value is the bending stiffness, which microscopic theories and measurements of phonon modes in graphite put at $\kappa_{\mathrm{0}}=$1.2 eV.$^{\mathrm{1}}$ However, theories of the effects of thermal fluctuations in 2D membranes predict that the bending stiffness at longer length scales could be orders of magnitude higher.$^{\mathrm{2,3}}$ This macroscopic value has not been measured. Here we present the first direct measurement of monolayer graphene's bending stiffness, made by mechanically lifting graphene off a surface in a liquid and observing both motion induced by thermal fluctuations and the deflection caused by gravity's effect on added weights. These experiments reveal a value $\kappa_{\mathrm{eff}}=$12 keV at room temperature --- four orders of magnitude higher than $\kappa_{\mathrm{0}}$. These results closely match theoretical predictions of the effects of thermally-induced fluctuations which effectively thicken the membrane, dramatically increasing its bending stiffness at macroscopic length scales. [1] A. Fasolino et al., Nat. Mater. (2007) [2] D. R. Nelson and L. Peliti, J Physique (1987) [3] F. L. Braghin and N. Hasselmann, Phys Rev B (2010) [Preview Abstract] |
Wednesday, March 20, 2013 1:27PM - 1:39PM |
N7.00010: Nonlinear Mechanics of Polycrystalline Two-Dimensional Materials such as Graphene Ryan Cooper, Adam Hurst, Alexandra Hammerberg, Gwan-Hyoung Lee, Christopher Marianetti, Xiaoding Wei, Changgu Lee, Bryan Crawford, James Hone, Jeffrey Kysar Two-dimensional films such as graphene can potentially exist as pristine crystals. These crystals present a unique opportunity to design unique experiments that uncover intrinsic material properties. Recent experimental studies have shown graphene is the strongest material ever measured. An Agilent G200 nanoindenter and Park Systems atomic force microscope are used in this study to make measurements of the mechanical response of graphene and other two-dimensional materials. Chemical vapor deposition is employed to manufacture graphene. The mechanical properties of the chemical vapor deposited graphene is compared to that of pristine graphene. Experiments investigate the elastic response up to the point of fracture. These suspended sheets are probed using atomic force microscopy and nanoindentation. The experimental work is modeled using first-principles density functional theory and finite element analysis. Previous work has shown that density functional theory and finite element analysis accurately predicts the breaking force of graphene and molybdenum disulfide. This work also explores the probability of fracture using a generalized form of the Weibull modulus in finite element analysis. [Preview Abstract] |
Wednesday, March 20, 2013 1:39PM - 1:51PM |
N7.00011: Electron transport measurement in locally strained graphene Hikari Tomori, Akinobu Kanda, Youiti Ootuka, Hiromasa Karube, Akinobu Kanda Strain engineering is a promising method for controlling electron transport in graphene; Spatial variation of gauge fields produced by non-uniform strain in graphene causes electron scattering, leading to modulation of the electronic state such as band gap formation. We have succeeded in introducing local strain to graphene, by inserting designed dielectric nanostructures between the graphene sheet and its substrate. [1] The transport measurement of strained graphene has revealed that improvement of the mean free path is crucial for clear demonstration of effect of lattice strain on electron transport.\\[4pt] [1] H. Tomori et al., Appl. Phys. Express 4, 075102 (2011). [Preview Abstract] |
Wednesday, March 20, 2013 1:51PM - 2:03PM |
N7.00012: Lubricating graphene with nanometer-thick perfluoropolyethers Lei Li, Andrew Kozbial, Steven Iasella, Alexander Taylor, Zhiting Li, Haitao Liu Due to its excellent optical, electrical and mechanical properties, graphene has found many important applications. Since graphene is atomic thick, the wear resistance is critical to the reliability of graphene-containing devices. In this study, both monolayer and multilayer graphene were coated with nanometer-thick perfluoropolyethers (PFPEs) and the effect of the nanolubricants on the wear and friction was investigated. The coefficient of friction (COF) was measured with a commercial nanotribometer and the wear was characterized with optically microscopy, AFM and Raman microscopy. Coated with PFPEs, monolayer graphene on silicon showed significantly decreased COF. However, the wear resistance was only slightly improved. For multilayer graphene on nickel substrate coated with PFPEs, COF also decreased significantly. Meanwhile, the wear resistance was improved substantially. The results were discussed based on the graphene-substrate adhesion and the thickenss of the graphene. The learning here potentially will lead to the methodology to improve the reliability of graphene-containing devices. [Preview Abstract] |
Wednesday, March 20, 2013 2:03PM - 2:15PM |
N7.00013: Temperature and size dependent friction of gold nanoislands on graphene Ben D. Dawson, Michael S. Lodge, Zachary Williams, Masa Ishigami Nanoscale motors and machines require the ability to tune frictional properties at the nanoscale. Yet a fundamental understanding of frictional processes of nanoislands still remains unknown. We have performed a quartz crystal microbalance study to investigate the role of temperature and island size on frictional energy dissipation for gold nanoislands on graphene. Significant frictional dissipation is observed even at room temperature, consistent with activated friction on the graphene surface. We will discuss these results and compare them to previously predicted models for thermally activated and size dependent friction. [Preview Abstract] |
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