Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session H40: Properties of Carbon Nanotubes |
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Sponsoring Units: DCMP Chair: Masa Ishigami, Univ of Central Florida Room: LACC 501C |
Tuesday, March 6, 2018 2:30PM - 2:42PM |
H40.00001: Automated circuit fabrication and direct characterization of carbon nanotubes vibrations - Optical imaging of CNTs Yuval Yaish, Gilad Zeevi, Michael Shlafman, Tal Tabachnik, Zeev Rogachevsky, Sharon Rechnitz, Israel Goldshtein, Shlomo Shlafman Since their discovery carbon nanotubes (CNTs) have fascinated many researchers due to their unprecedented electrical, optical, thermal, and mechanical properties. However, a major drawback in utilizing CNTs for practical applications is the difficulty in positioning or growing them at specific locations. |
Tuesday, March 6, 2018 2:42PM - 2:54PM |
H40.00002: Intersubband plasmons in gated and aligned single-wall carbon nanotubes Kazuhiro Yanagi, Yota Ichinose, Ryotaro Okada, Yohei Yomogida, Fumiya Katsutani, Weilu Gao, Junichiro Kono Intersubband transitions (ISBTs) occur in doped semiconductor quantum wells (QWs) as resonant optical transitions between subbands within the conduction or valence band. They are the elementary optical process in quantum-engineered infrared (IR) optoelectronic devices, such as the QW IR photodetector and the quantum cascade laser. From a fundamental point of view, ISBTs represent the collective, plasmonic response of quantum-confined carriers to an oscillating electric field applied along the confinement direction, whose resonance frequency is strongly influenced by a variety of many-body effects. Here, we describe the first clear evidence for ISBTs in single-wall carbon nanotubes. We observed the appearance of a large optical absorption peak in the near-IR for excitation light polarized perpendicular to the nanotube axis only when carriers were created in the lowest-energy subband, either in the conduction or valence band, through ionic-gel gating. |
Tuesday, March 6, 2018 2:54PM - 3:06PM |
H40.00003: Single carbon nanotubes as ultrasmall all-optical memories Takushi Uda, Akihiro Ishii, Yuichiro Kato Performance improvements are expected from integration of photonic devices into information processing systems, and in particular, all-optical memories provide a key functionality. Scaling down the size of memory is desirable for high-density integration, and the use of nanomaterials would allow for devices that are significantly smaller than the operation wavelengths. Here we report on all-optical memory based on individual carbon nanotubes, where adsorbed molecules give rise to optical bistability [1]. By exciting at the high-energy tail of the excitonic absorption resonance, nanotubes can be switched between the desorbed state and the adsorbed state. We demonstrate reversible and reproducible operation of the nanotube optical memory, and determine the rewriting speed by measuring the molecular adsorption and desorption times. Our results underscore the impact of molecular-scale effects on optical properties of nanomaterials, offering new design strategies for photonic devices that are a few orders of magnitude smaller than the optical diffraction limit. |
Tuesday, March 6, 2018 3:06PM - 3:18PM |
H40.00004: Probing the non-linear transient response of a carbon nanotube mechanical oscillator Kyle Willick, Xiaowu (Shirley) Tang, Jonathan Baugh Carbon nanotube (CNT) nano-electromechanical systems have demonstrated unprecedented sensitivities for detecting small masses and forces. In cryogenic measurement setups, the detection speed of the mechanical resonator amplitude is usually limited by the CNT contact resistance and parasitic capacitance of cabling. We report the use of a cold heterojunction bipolar transistor (HBT) amplifying circuit near the device to measure the mechanical amplitude at microsecond timescales. A Coulomb rectification scheme, in which the probe signal is at much lower frequency than the mechanical drive signal, allows investigation of the strongly non-linear regime. The behaviour of transients in both the linear and non-linear regimes is observed and modeled by including Duffing and non-linear damping terms in a harmonic oscillator equation. We show that the non-linear regime can result in faster mechanical response times, on the order of 10 µs for the device and circuit presented. (arXiv: 1707.03025) |
Tuesday, March 6, 2018 3:18PM - 3:30PM |
H40.00005: Perovskite Solar Cells using Carbon Nanotubes both as Cathode and Anode Seungju Seo, Il Jeon, Yuta Sato, Clement Delacou, Anton Anisimov, Kazu Suenaga, Esko Kauppinen, Yutaka Matsuo, Shigeo Maruyama Organic-inorganic halide perovskite solar cells (PSCs) have received much attention on account of their high power conversion efficiency while providing the advantages of solution processability and potentially low fabrication cost. However, at the current level of halide perovskite solar cell technology, these advantages cannot be maximized due to structural and material limitations. Here, we provide a solution to these problems by all-carbon nanotube (CNT) electrode-based PSCs that employ fully solution-processed layers. This study has two central aims: to demonstrate the use of CNT films as both the anode and cathode and to devise an entirely solution-processed configuration with a rational cost analysis. We show that [6,6]-phenyl C61-butyric acid methyl ester (PC61BM)-soaked CNTs can function as the cathode, and also that poly(3-hexylthiophene-2,5-diyl) (P3HT)-soaked CNTs can function as the anode, playing a role in energy alignment. Our flexible fully solution-processed all-CNT-electrode PSCs, with a configuration of CNT-P3HT/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) /CH3NH3PbI3 (MAPbI3)/CNT-PC61BM, gave a PCE of 7.32% with good mechanical flexibility. This work realizes innovations in the materials, costs, and processing of inverted-type PSCs. |
Tuesday, March 6, 2018 3:30PM - 3:42PM |
H40.00006: Emission enhancement of air-suspended carbon nanotubes using air-mode nanobeam cavities Hidenori Machiya, Takushi Uda, Akihiro Ishii, Yuichiro Kato We design high quality factor air-mode nanobeam cavities by finite-difference time-domain simulations, and utilize the cavities to enhance the emission of air-suspended carbon nanotubes [1]. The cavities are fabricated from silicon-on-insulator wafers, and nanotubes are synthesized over the cavities by chemical vapor deposition. Photoluminescence spectroscopy is performed on the devices, where we observe optical coupling when the nanotube emission energy is close to the cavity resonance. Taking advantage of laser-heating-induced blueshifts of the nanotube emission, we can reduce the detunings [2]. We derive and numerically calculate the generalized expression for the spectral overlap, and a good correlation to the enhancement factors is obtained. |
Tuesday, March 6, 2018 3:42PM - 3:54PM |
H40.00007: Strong and broadly tunable plasmon resonances in thick films of aligned carbon nanotubes Abram Falk, Po-Hsun Ho, Kuan-Chang Chiu, Damon Farmer, George Tulevski Low-dimensional plasmonic materials can function as high quality terahertz and infrared antennas at deep subwavelength scales. Despite these antennas’ strong coupling to electromagnetic fields, there is a pressing need to further strengthen their absorption. We address this problem by fabricating thick films of aligned, uniformly sized semiconducting carbon nanotubes and showing that their plasmon resonances are strong, narrow, and broadly tunable [1,2]. With thicknesses ranging from 25 to 250 nm, our films exhibit peak attenuation reaching 70%, ensemble quality factors reaching 9, and electrostatically tunable peak frequencies by a factor of 2.3. Excellent nanotube alignment leads to the attenuation being 99% linearly polarized along the nanotube axis. Increasing the film thickness blueshifts the plasmon resonators down to peak wavelengths as low as 1.4 μm, a new near-infrared regime in which they can both overlap the S11 nanotube exciton energy and access the technologically important infrared telecom band. |
Tuesday, March 6, 2018 3:54PM - 4:06PM |
H40.00008: Probing Graphene Hydrodynamics with a Carbon Nanotube via Coulomb Drag Laurel Anderson, Austin Cheng, Takashi Taniguchi, Kenji Watanabe, Philip Kim In the hydrodynamic regime, where the electron-electron scattering length is smaller than the elastic scattering length, the collective behavior of the electrons in graphene is predicted to resemble a viscous fluid. When two mesoscopic conductors are isolated but closely spaced, a current driven in one layer induces a current in the proximate conducting layer via the Coulomb interaction between electrons in different layers. This Coulomb drag effect has been shown to occur between carbon nanotubes and graphene separated by a few-layer hexagonal boron nitride crystal. We employ an individually isolated carbon nanotube as a controllable 1D perturbation to create the shearing drag forces in the graphene that result in the viscous behaviors characteristic of the hydrodynamic regime. By examining the spatial dependence of the drag signal, we can deduce the pattern of the hydrodynamic flow in graphene at different doping levels. Our preliminary results at high carrier density (in the Fermi liquid regime) indicate sign changes of the drag response as distance from the carbon nanotube-induced current increases. |
Tuesday, March 6, 2018 4:06PM - 4:18PM |
H40.00009: Fabrication and Characterization of Aligned Metallic Carbon Nanotube Thin Films Joshua Walker, Henry Wladkowski, William Rice The one-dimensional nature of individualized single wall carbon nanotubes (SWCNTs) allows for them to exhibit highly anisotropic mechanical, optical, electrical, and thermal behaviors. However, producing macroscopic alignment of SWCNT ensembles has proven difficult, which has hindered scientific and industrial investigations into their anisotropic properties. Here, we explore the optical and electronic behavior of aligned, metallic SWCNT thin films, produced using a slow vacuum filtration method. We measure the degree of nanotube alignment using a variety of polarized optical measurements, including optical imaging, Raman, terahertz, and absorption spectroscopy. From these techniques, we observe a nematic ordering parameter of 0.3, which is confirmed via polarized Raman spectroscopy. The high metallicity of these films, and the strong, anisotropic absorption of the metallic nanotubes, suggests their potential use as a broadband linear polarizer. |
Tuesday, March 6, 2018 4:18PM - 4:30PM |
H40.00010: Nonlinear Terahertz Carrier Dynamics in Free-Standing Carbon Nanotubes Ali Mousavian, Byounghwak Lee, Michael Paul, Zachary Thompson, Andrew Stickel, Yun-Shik Lee Carbon nanotubes (CNTs) have exceptional electrical and optical properties which have inspired unique applications in nanoscale optoelectronics. High speed electronics demands the studies of CNTs at THz frequencies, particularly in high-field regime. We present an experimental study on nonlinear anisotropic response of unidirectionally aligned multi-walled CNTs (MWCNTs). Free-standing MWCNTs form a quasi-one-dimensional semi-metallic structure and exhibit highly nonlinear THz responses when the THz polarization is parallel to the CNT axis, while no nonlinear THz effects are observed for the perpendicular polarization. Unlike a typical conducting medium in which strong THz pulses induce transparency, intense THz fields enhance absorption in MWNTs, which suggests that strong THz fields efficiently generate charge carriers in MWNTs. The experimental data of THz time-domain spectroscopy and the theoretical analysis based on Drude-Lorentz model indicates that intense THz pulses enhance permittivity in CNTs via carrier generation and multiplication. The nonlinear THz effects undergo an extraordinary transition when CNTs are optically excited. THz fields of the intermediate range (~600 kV/cm) suppress the mobility of the photocarriers in CNTs. |
Tuesday, March 6, 2018 4:30PM - 4:42PM |
H40.00011: Robust Secondary Electron Interference in Suspended Carbon Nanotubes Neda Lotfizadeh, Daniel McCulley, Mitchell Senger, Ethan Minot, Vikram V. Deshpande Quantum interference of electron waves in devices with the size close to the electron coherence length has been studied in various fields such as Aharonov-Bohm and quantum Hall effect. Fabry-Perot (FP) oscillations arise from electron interferences in carbon nanotubes and can be seen as conductance oscillations as a function of gate voltage [1]. Electron interferences can cause another oscillation in addition to FP in carbon nanotubes [2]. Dirnaichner et al observed these oscillations and suggested that they come from the symmetry of the carbon nanotubes [3]. These oscillations have been referred to as slow oscillations due to their larger period compare to the FP oscillations. |
Tuesday, March 6, 2018 4:42PM - 4:54PM |
H40.00012: Resonance Raman Signature of Intertube Excitons in (6,5)-Enriched Carbon Nanotube Bundles Jeffrey Simpson, Oleksiy Roslyak, Andrei Piryatinski, Angela Hight Walker, Stephen Doorn Electronic interactions in low-dimensional nanomaterial heterostructures can lead to novel optical response arising from exciton delocalization over the constituent materials. Similar phenomena have been suggested to arise between closely interacting semiconducting single wall carbon nanotubes (SWCNTs) of identical structure. We use resonance Raman spectroscopy (RRS) to probe intertube interactions in (6,5)-enriched SWCNTs, dispersed in aqueous solutions and separated using density gradient ultracentrifugation into fractions of increasing bundle size. A continuously tunable dye laser coupled to a triple-grating spectrometer affords measurement of Raman resonance excitation profiles (REPs) over a range of wavelengths, (505 to 585)nm, covering the (6,5)-E22S excitation. REPs of both the radial breathing mode (RBM) and GLO+ display a previously unobserved sharp feature that is superimposed on the typical intrinsic exciton resonance response. This sharp feature provides evidence for the creation of intertube excitons, with the response being generated as the result of the interaction between the intratube and intertube excitons whose spectral responses overlap. |
Tuesday, March 6, 2018 4:54PM - 5:06PM |
H40.00013: Fano resonances in Raman response of carbon nanotube bundles as signature of interacting excitons Andrei Piryatinski, Oleksiy Roslyak, Jeffrey Simpson, Angela Hight Walker, Stephen Doorn Electronic interactions in low-dimensional nanomaterial heterostructures can lead to novel optical response arising from exciton delocalization over the constituent materials. Similar phenomena have been suggested to arise between closely interacting semiconducting single wall carbon nanotubes (SWCNTs) of identical structure. While not yet probed in detail, such behavior in SWCNTs has potential to open a path to new exciton physics, impact exciton transport mechanisms in SWCNT networks, and place SWCNTs as one-dimensional models for such behaviors in systems of higher dimensionality. Motivated by experimental studies on high purity bundles of (6,5) SWCNTs, we develop a scattering model for interacting intertube and intratube excitons in SWCNT bundles. Based on this model, the bundle Raman response is examined and the Raman excitation spectra are modeled. Our analysis shows that the scattering of bright intratube exciton by dark intertube one results in a sharp anomalous spectral feature identified as the Fano resonance. Furthermore, the universality of the model suggests that similar Raman excitation profile features may be observed for interlayer exciton resonances in 2D multilayered systems. |
Tuesday, March 6, 2018 5:06PM - 5:18PM |
H40.00014: Experimental observation of the Wigner cusps in a metallic carbon nanotube Masa Ishigami, Brandon Blue, Ryuichi Tsuchikawa, Amin Ahmadi, Daniel Heligman, Zhenghi Zhang, James Hone, Eduardo Mucciolo The Wigner cusp is a phenomenon observed in nuclear physics. The cusp is manifested in condensed matter physics in theoretical calculations of scattering induced by impurities: the impurity scattering is highly enhanced as the energy of charge carriers near the threshold energies for another conduction subbands. Such effects are commonly seen in transport calculations of carbon nanotubes and graphene nanoribbons. Yet, the Wigner cusp has never been observed experimentally in condensed matter systems. |
Tuesday, March 6, 2018 5:18PM - 5:30PM |
H40.00015: Performance of Solution-Processed Carbon Nanotube Field Effect Transistors using Graphene Electrodes P R Yasasvi Gangavarapu, Punith C Lokesh, K N Bhat, A K Naik Carbon nanotube field effect transistors (CNTFETs) are considered to be the strong contenders to replace Si in future nanoelectronics because of their excellent electronic, mechanical and thermal properties. In this work we assess the performance of both p-type and n-type CNTFETs using few layer graphene as the contact electrode material. We have performed temperature dependent I–V measurements and the Schottky barrier height at CNT–graphene junction has been extracted. The calculated barrier height at CNT–graphene junction is close to zero for both p-CNTFETs and n-CNTFETs. This signifies the Ohmic contact of graphene with both valence and conduction bands of CNTs and that graphene can provide low barrier contact for both hole and electron transport in CNTFETs. In addition, we observe that there is no correlation between the thickness of graphene and the barrier height estimated. Our work demonstrates the suitability of graphene as contact electrode material for Complementary logic circuits based on CNTFETs. |
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