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Optical Spectroscopy Of Individual Single Walled Carbon Nanotubes In An Electric Gate Structure
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Book Synopsis Optical Spectroscopy of Individual Single-walled Carbon Nanotubes in an Electric Gate Structure by : Jan Tibor Glückert
Download or read book Optical Spectroscopy of Individual Single-walled Carbon Nanotubes in an Electric Gate Structure written by Jan Tibor Glückert and published by . This book was released on 2014 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Spectroscopy of Individual Single-Walled Carbon Nanotubes by : Oliver Kiowski
Download or read book Spectroscopy of Individual Single-Walled Carbon Nanotubes written by Oliver Kiowski and published by Sudwestdeutscher Verlag Fur Hochschulschriften AG. This book was released on 2011-10 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: A thermal chemical vapor deposition (CVD) reactor was built and used to grow vertically and horizontally aligned carbon nanotube arrays. The as-grown nanotubes were investigated on a single tube level using near-infrared photoluminescence (PL) microscopy and PL excitation spectroscopy as well as Raman, atomic force and scanning electron microscopy. The PL of single-walled carbon nanotubes (SWNT) in different surroundings and at temperatures down to 4 K was analyzed. Ultralong CVD-grown nanotubes were imaged on Si/SiO2 to determine their chirality and to check structural integrity along the nanotube length. Furthermore, ultralong SWNTs were manipulated (moved, bent and fractured) employing an AFM. Finally, a new approach to determine relative abundances and PL quantum yields of semiconducting SWNTs in dispersions is presented, which is based on statistical counting of individual nanotubes by means of PL spectroscopy.
Book Synopsis Optical and Electrical Properties of Single-walled Carbon Nanotubes with Known Chiralities by : Zhengyi Zhang
Download or read book Optical and Electrical Properties of Single-walled Carbon Nanotubes with Known Chiralities written by Zhengyi Zhang and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotube (CNT) is a hollow structure consisted by one-atom-thick sheet of carbon atoms, which can be considered as a rolled-up graphene sheet. The diameter and rolling angle (chirality) uniquely determines its electronic structure. Over two decades of study, due to the difficulty of synthesizing clean individual CNTs and the limitation of accurate chirality characterization, there are still unveiled questions towards the intrinsic properties of this 1-D material at single molecular level. In this thesis, I will discuss the approaches of fabricating chirality assigned CNT device and the experimental results of its optical and electrical properties. In the first part, I describe using 'fast heating' chemical vapor deposition (CVD) method to achieve the high quality suspended CNT growth. Combining Rayleigh and Raman spectroscopy, I demonstrate the accurate assignment of chirality for each suspended individual CNT. With the ability of chirality identification, a series of optical and electrical experiments were conducted on the selected CNTs of interest.
Book Synopsis Electrical Characterization and Device Applications of Individual Singled-wall Carbon Nanotubes by : Ali Javey
Download or read book Electrical Characterization and Device Applications of Individual Singled-wall Carbon Nanotubes written by Ali Javey and published by . This book was released on 2005 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Carbon nanotubes and graphene for photonic applications by : K. Matsuda
Download or read book Carbon nanotubes and graphene for photonic applications written by K. Matsuda and published by Elsevier Inc. Chapters. This book was released on 2013-08-31 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fundamental electronic states and optical properties of single-walled carbon nanotubes are briefly explained in this chapter. Moreover, the novel optical properties of carbon nanotubes revealed by advanced laser spectroscopy (single-nanotube spectroscopy and time-resolved spectroscopy) are introduced. Due to the enhanced Coulomb interaction, the optically generated electron-hole pair forms a strongly bound ‘exciton’ state, analogous to the hydrogen-like state in the carbon nanotubes. The striking features of excitons in the carbon nanotube, such as singlet-dark states and triplet states, which dominate the optical properties, are described in this chapter.
Book Synopsis Springer Handbook of Nanomaterials by : Robert Vajtai
Download or read book Springer Handbook of Nanomaterials written by Robert Vajtai and published by Springer Science & Business Media. This book was released on 2013-08-20 with total page 1234 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Springer Handbook of Nanomaterials covers the description of materials which have dimension on the "nanoscale". The description of the nanomaterials in this Handbook follows the thorough but concise explanation of the synergy of structure, properties, processing and applications of the given material. The Handbook mainly describes materials in their solid phase; exceptions might be e.g. small sized liquid aerosols or gas bubbles in liquids. The materials are organized by their dimensionality. Zero dimensional structures collect clusters, nanoparticles and quantum dots, one dimensional are nanowires and nanotubes, while two dimensional are represented by thin films and surfaces. The chapters in these larger topics are written on a specific materials and dimensionality combination, e.g. ceramic nanowires. Chapters are authored by well-established and well-known scientists of the particular field. They have measurable part of publications and an important role in establishing new knowledge of the particular field.
Book Synopsis Nonlinear Optical Spectroscopy of Isolated Single-walled Carbon Nanotubes by : Tatyana Sheps
Download or read book Nonlinear Optical Spectroscopy of Isolated Single-walled Carbon Nanotubes written by Tatyana Sheps and published by . This book was released on 2011 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: Single-walled and multi-walled carbon nanotubes (SWNTs) and (MWNTs) are low dimensional conductors with unique electronic and electro optic properties. To probe these properties, we investigate the third-order, coherent anti-Stokes (CAS) response of individual SWNTs using a dual color, four-wave-mixing technique. Despite being nanoscale objects much smaller than the wavelength of light, the CAS response allows single SWNTs to be optically imaged with good spatial resolution using picosecond infrared laser excitation pulses and a diffraction limited, confocal microscopy technique. The absence of a pronounced Raman signature shows that the CAS response is dominated by electronic rather than vibrational dynamics. The dependence of the CAS signal on fundamental morphological properties of nanotubes is investigated and characterized. The nonlinear signal is found to depend strongly on nanotube diameter and polarization angle while the dependence on length and individual nanotube chirality is much less clear. The CAS signal is also strongly dependent on metallicity, allowing for straightforward optical discrimination between metallic and semiconducting SWNTs. However, variability of undetermined origin still exists in the CAS signal intensity from a given nanotube type. This variability may depend on electrical contact resistances, charge carrier densities, and local physiochemical effects. Furthermore, identification of the third-order CAS response in SWNTs requires proper accounting for other nonlinear luminescence mechanisms. The SWNT and MWNT optical response is found to contain contributions from competing multi-photon processes, including third-order vibrational and electronic mechanisms as well as second-order fluorescence. The relative intensity of these nonlinear processes is investigated and compared.
Book Synopsis Electronic Characterization of Individual Single-Walled Carbon Nanotubes by : Chi-Yan Wong
Download or read book Electronic Characterization of Individual Single-Walled Carbon Nanotubes written by Chi-Yan Wong and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Electronic Characterization of Individual Single-walled Carbon Nanotubes" by Chi-yan, Wong, 王志仁, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled ELECTRONIC CHARACTERIZATION OF INDIVIDUAL SINGLE-WALLED CARBON NANOTUBES Submitted by Wong Chi Yan for the Degree of Master of Philosophy at The University of Hong Kong in September 2007 The outstanding properties of carbon nanotubes (CNTs) have attracted con- siderable research effort in the last decade. CNTs are quasi-one-dimensional materials which can be used to study fundamental quantum effects of one- dimensional systems. TherehasbeenagreatdealofinterestspecificallyinsemiconductingCNTs, which have shown to be promising candidates as the building blocks for the next-generation electronic applications. Carbon nanotube electronic devices have the potential to replace conventional silicon-based counterparts. How- ever, there are still obstacles that remain with regard to the scientific study or application oriented researches. For example, the growth orientation and the band gaps of individual CNTs are difficult to control. In addition, pronounced low-frequency current fluctuation, 1/f noise, exists. The measured noise levelisevencomparabletothesignallevelundersomecircumstances, therebylimit- ing the application of CNTs in low-signal electronics and the overall reliability of CNT based devices. In this thesis, single-walled CNTs (SWNTs) were chosen as a studying modelduetotheirsimplicityinnature. DifferentmethodsofindividualSWNT fieldeffecttransistor(FET)fabricationmethodswerecompared. Themethods included: (I) Directed growth of ultra long SWNTs on a wafer by CVD using ethanol, and (II) Dispersing the SWNTs fabricated by ordinary CVD, on the wafer with organic solvents. The noise behavior for both fabrication methods were characterized by DAQ and lock-in noise measurement methods. Thereafter, thebasicI-V measurementsoffabricatedSWNTFETdevices were also performed. The hysteresis effect and its time dependent measure- ments in FETs were illustrated. The measurements results suggested that the hysteresis effect in nanotube devices was attributed to the charge traps in the oxide layer of FETs. Finally, the 1/f noise of SWNT FETs was studied. It was shown that the 1/f noise arose from the carrier number fluctuations rather than mobility fluctuations, as a superposition of Lorentzian fluctuation spectra. The corre- -2 sponding Hooge constant was found to be gate dependent and about 10 in thelinearregime. Bycomparingwiththereportedsimulationresultofrandom telegraphsignal(RTS)noiseamplitudeinsubthresholdregime, itwasproposed that such Lorentzian fluctuation spectra were due to the RTS noise, arising from the gate potential fluctuations in the CNT, and the charge exchange be- tween CNT and oxide layer. These potential fluctuations were attributed to trapped charges in the oxide nearby which changed the number of carriers in the CNTs. DOI: 10.5353/th_b3955704 Subjects: Nanotubes Nanostructured materials - Electric properties Transistors
Book Synopsis Carbon nanotubes and graphene for photonic applications by : W. Walden-Newman
Download or read book Carbon nanotubes and graphene for photonic applications written by W. Walden-Newman and published by Elsevier Inc. Chapters. This book was released on 2013-08-31 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Single-walled carbon nanotubes (SWCNTs) have recently attracted tremendous interest as a nanomaterial for photonics and quantum photonics devices. Here we shall review recent work with a focus on quantum light properties such as blinking and spectral diffusion, and in particular, methods and techniques to suppress these detrimental effects with the goal of enhancing optical emission. Furthermore, we shall review recent work on the generation and detection of nonclassical light emissions from individual SWCNTs embedded in polymer cavities, and discuss the role of spatial exciton localization along the tube.
Book Synopsis Probing the Band Gap Structure of Single-walled Carbon Nanotubes by Optical Spectroscopy by : Lain-Jong Li
Download or read book Probing the Band Gap Structure of Single-walled Carbon Nanotubes by Optical Spectroscopy written by Lain-Jong Li and published by . This book was released on 2006 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Investigations Into the Optical Properties of Individual, Air-suspended, Single-walled Carbon Nanotubes by : Mark William Brennan Wilson
Download or read book Investigations Into the Optical Properties of Individual, Air-suspended, Single-walled Carbon Nanotubes written by Mark William Brennan Wilson and published by . This book was released on 2008 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: Single-walled carbon nanotubes are naturally-forming nanostructures that have attracted considerable recent research interest due to their unique opto-electronic properties and comparative ease of fabrication. Two-thirds of nanotube species are semiconductors due to symmetry conditions imposed by their pseudo-one-dimensional tubular structure, and exhibit band-gap photoluminescence when isolated from their environment. Despite their elegant structural simplicity, fundamental properties of carbon nanotubes, such as their intrinsic quantum efficiency, non-linear excitonic recombination mechanisms, and the role of environmental effects, continue to be disputed in the literature. The design of an apparatus capable of observing nanotube photoluminescence is presented, along with conclusive proof of the observation of a single (9,8)-chirality nanotube in the form of spectral, spatial, and polarization-dependent measurements. The dependance of the excitation and emission spectra of a single nanotube on the excitation intensity is explored and the emission spectra found to be described by a Gaussian peak function, in contrast to previously-reported results. The unexpected ability to cause redshifts in the emission spectrum via the ambient humidity is discovered, which has consequences on experimental best practices. Photoluminescence quantum efficiencies are measured to be 4"2% and 13"6% for two different nanotubes. This is at the high end of the range for comparable literature results, and supports the validity of a recent literature value for the effective atomic absorption coefficient for carbon, AC=1.6 x 10^- 3nm^2, which is ten times greater than previous literature values. Pulsed power dependence studies show that the PL emission undergoes 'hard' saturation at an excitation intensity of 0.5 x 10^12photons/pulse/cm2, which is at least 100 times lower than previous reports and provides insight into non-linear decay dynamics. A novel theoretical model is developed to explain this saturation process, which yields an absorption co-efficient of AC=1.2"0.3 x 10^ - 3nm^2 as a fit parameter. Time-resolved photoluminescence dynamics are explored using femtosecond excitation correlation spectroscopy. Results suggest that the one-body decay processes are bi-exponential, with time constants of 31"4ps and 313"61ps, but also highlight the limitations of this technique in observing the expected very rapid (~1 ps) two-body Auger recombination process.
Book Synopsis Quantitative Optical Imaging of Single-walled Carbon Nanotubes by : Lihong Huang Herman
Download or read book Quantitative Optical Imaging of Single-walled Carbon Nanotubes written by Lihong Huang Herman and published by . This book was released on 2013 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development and application of optical imaging tools and probing techniques have been the subject of exciting research. These tools and techniques allow for non-invasive, simple sample preparation and relatively fast measurement of electronic and optical properties. They also provided crucial information on optoelectronic device application and development. As the field of nanostructure research emerged, they were modified and employed to understand various properties of these structures at the diffraction limit of light. Carbon nanotubes, up to hundreds of micrometers long and several nanometers thin, are perfect for testing and demonstrating newly-developed optical measurement platforms for individual nanostructures, due to their heterogeneous nature. By employing two quantitative imaging techniques, wide-field on-chip Rayleigh scattering spectroscopy and spatial modulation confocal absorption microscopy, we investigate the optical properties of single-walled carbon nanotubes. These techniques allow us to obtain the Rayleigh scattering intensity, absolute absorption cross section, spatial resolution, and spectral information of single-walled carbon nanotubes. By probing the optical resonance of hundreds of single-walled carbon nanotubes in a single measurement, the first technique utilizes Rayleigh scattering mechanism to obtain the chirality of carbon nanotubes. The second technique, by using high numerical aperture oil immersion objective lenses, we measure the absolute absorption cross section of a singlewalled carbon nanotube. Combining all the quantitative values obtained from these techniques, we observe various interesting and recently discovered physical behaviors, such as long range optical coupling and universal optical conductivity on resonance, and demonstrate the possibility of accurate quantitative absorption measurement for individual structures at nanometer scale.
Book Synopsis Carbon Nanotubes by : Siva Yellampalli
Download or read book Carbon Nanotubes written by Siva Yellampalli and published by BoD – Books on Demand. This book was released on 2011-07-20 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon nanotubes are one of the most intriguing new materials with extraordinary properties being discovered in the last decade. The unique structure of carbon nanotubes provides nanotubes with extraordinary mechanical and electrical properties. The outstanding properties that these materials possess have opened new interesting researches areas in nanoscience and nanotechnology. Although nanotubes are very promising in a wide variety of fields, application of individual nanotubes for large scale production has been limited. The main roadblocks, which hinder its use, are limited understanding of its synthesis and electrical properties which lead to difficulty in structure control, existence of impurities, and poor processability. This book makes an attempt to provide indepth study and analysis of various synthesis methods, processing techniques and characterization of carbon nanotubes that will lead to the increased applications of carbon nanotubes.
Book Synopsis Optical Absorption and Electronic Properties of Individual Carbon Nanotubes by : Jean-Christophe Blancon
Download or read book Optical Absorption and Electronic Properties of Individual Carbon Nanotubes written by Jean-Christophe Blancon and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation, we report on the experimental investigation of the optical properties of single- and double-wall carbon nanotubes. Despite numerous studies performed using photoluminescence or Raman and Rayleigh scattering, knowledge of their optical response is still partial. In particular direct quantitative measurement of their absorption cross-section has not been achieved yet. Using spatial modulation spectroscopy we have determined, over a broad optical spectral range, the spectrum and amplitude of the absorption cross-section of identified individual single- and double-wall carbon nanotubes. These quantitative measurements permit the determination of the oscillator strength of the different excitonic resonances. Furthermore, investigation of the same nanotube, either a single-wall or double-wall nanotube, freestanding or deposited on a substrate shows large broadening with increase of oscillator strength of the excitonic resonances, as well as stark weakening of polarization dependent antenna effects, due to nanotube-substrate interaction. Similar study on nanotube bundles and double-wall nanotubes demonstrate the importance of inter-tube and inter-wall exciton coupling effects which seem to be of different nature in these two types of sample. The second part of this thesis studies electrical transport in carbon nanotube bundles under high pressure condition and low temperature. The behavior of nanotubebased field-effect transistors has been investigated, in the classical and Coulomb blockade regime, under gas-pressure up to 0.9 GPa. Overall, this dissertation communicates on the quantitative analysis of the absorption and electronic properties of carbon nanotubes and how they are influenced by various environmental effects such as dielectric screening, stress induced strain, hydrostatic pressure, or chemical doping. The novelty of this work is to address these issues at the single nanotube level.
Book Synopsis Graphene and Carbon Nanotubes by : Ermin Malic
Download or read book Graphene and Carbon Nanotubes written by Ermin Malic and published by John Wiley & Sons. This book was released on 2013-04-12 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: A first on ultrafast phenomena in carbon nanostructures like graphene, the most promising candidate for revolutionizing information technology and communication The book introduces the reader into the ultrafast nanoworld of graphene and carbon nanotubes, including their microscopic tracks and unique optical finger prints. The author reviews the recent progress in this field by combining theoretical and experimental achievements. He offers a clear theoretical foundation by presenting transparently derived equations. Recent experimental breakthroughs are reviewed. By combining both theory and experiment as well as main results and detailed theoretical derivations, the book turns into an inevitable source for a wider audience from graduate students to researchers in physics, materials science, and electrical engineering who work on optoelectronic devices, renewable energies, or in the semiconductor industry.
Book Synopsis Optical Spectroscopy of Bound Excitonic States in Single Walled Carbon Nanotubes by : Silvia Morim Santos
Download or read book Optical Spectroscopy of Bound Excitonic States in Single Walled Carbon Nanotubes written by Silvia Morim Santos and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation we report on original experimental investigations of the photophysical properties of individual single-walled carbon nanotubes (SWCNTs) at the single molecule level. We focused on two problems: the effect of water-filling nanotubes on their photoluminescence (PL) properties and generation of multi-excitonic complexes in regimes of strong laser excitation. To do so we used a combination of microscopy, PL spectroscopy and PL time decay measurements. Our results show, for different nanotube diameters, a red-shift of the PL emission energy for water-filled nanotubes. Furthermore, biexponential PL time decay behaviors are obtained for individual water-filled and empty (6,4) SWCNTs. The characteristic decay times for both species of nanotubes are distinct, with a reduction of the short component in water-filled SWCNTs. These results are explained by an increase of the dielectric constant for water-filled nanotubes. Our most consequential experimental result was the observation of all optical trion generation in undoped nanotubes. Trion emission appears in the PL spectrum as a red-shifted sideband. Based on our experimental observations, we propose a trion generation model according to which, at a multiexcitonic regime, exciton-exciton annihilation interactions create charge carriers that are transiently trapped at electrostatic potential fluctuations induced by the inhomogeneities of the environment. Subsequent photon absorption leads to trion formation localized at the trapped carriers.
Book Synopsis Scanning Photocurrent Microscopy Study of Photovoltaic and Thermoelectric Effects in Individual Single-walled Carbon Nanotubes by : Tristan DeBorde
Download or read book Scanning Photocurrent Microscopy Study of Photovoltaic and Thermoelectric Effects in Individual Single-walled Carbon Nanotubes written by Tristan DeBorde and published by . This book was released on 2014 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon Nanotubes are a unique family of nanostructures that have shown remarkable promise for mechanical, electrical, and optical applications. Fundamentally similar to the earlier discovered Buckminsterfullerene (C60), carbon nanotubes are hollow cylinders formed from a single sheet of carbon atoms. The research presented in this dissertation investigates several carbon nanotube properties, with an emphasis on the interactions between light and electrons within the nanotube. Better understanding of these optoelectronic properties is of great interest for future advancement in solar energy conversion. Carbon nanotubes are a quintessential material for researchers studying nanoscience. Small changes in nanotube structure can lead to striking differences in electrical and optical properties. In addition to this rich variety of properties, nanotubes can be concentrically inset within one another resulting in single-walled, double-walled, and multi-walled versions. Single-walled carbon nanotubes are desirable for optoelectronic study as complicated interactions between shells are avoided; which, while an interesting topic, is beyond the scope of this work. In the past, determination of carbon nanotube wall number was achieved via transmission electron microscopy, a technique requiring difficult sample preparation, making it impractical for most working devices. This thesis presents an alternative technique based on the compressibility of nanotube sidewalls as measured by atomic force microscopy. This technique is readily applicable to common device designs and can distinguish single and double-walled carbon nanotubes. This technique has been applied to characterizing the output of our growth process, resulting in recipes that highly favor single-walled growth. The optical properties of single-walled carbon nanotubes have been studied intensely. Each single-walled nanotube has an optical fingerprint based on its unique atomic structure. Specific single-walled nanotube structures can be selected for a wide range of optical applications. Again, however, most techniques previously used to study these optical properties are not easily transferable to common device designs. In this research, the measurement of nanotube fingerprints is achieved by optoelectronic means through the use of a newly constructed scanning photocurrent microscope. This instrument measures changes in electrical transport as the device is locally illuminated by a spectrally-tunable light source, making it a versatile tool for studying nanostructures implemented in a variety device designs. Early work on nanotube optoelectronic properties attributed photocurrent generation to a photovoltaic mechanism. This thesis, however, shows that strong photothermoelectric effects can also be present in nanotube optoelectronic devices. Light absorbed by a nanostructure can locally raise the temperature, resulting in thermoelectric currents. If a carbon nanotube is being employed as the absorbing element of a solar cell, it is possible for thermoelectric currents to reduce or enhance the efficiency of energy conversion. The last portion of this work investigates the nature of optically generated thermoelectric effects in carbon nanotubes. With a better understanding of these thermoelectric effects, future nanostructure solar cell design can efficiently utilize thermoelectric currents.
