Subramoney Applied Physics of Carbon Nanotubes

Fundamentals of Theory, Optics and Transport Devices
1. Auflage 2005
ISBN: 978-3-540-28075-0
Verlag: Springer-Verlag
Format: PDF
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 349 Seiten

The book describes the state of the art in fundamental, applied and device physics of nanotubes, including fabrication, manipulation and characterization for device applications; optics of nanotubes; transport and electromechanical devices and fundamentals of theory for applications. This information is critical to the field of nanoscience since nanotubes have the potential to become a very significant electronic material for decades to come.

The book will benefit all readers interested in the application of nanotubes, either in their theoretical foundations or in newly developed characterization tools that may enable practical device fabrication.

Written for Scientists

Keywords: Applied physics
Nanotube electronics
Nanotube optics
Nanotube synthesis
Nanotube theory

Autoren/Hrsg.

Subramoney, Shekhar

Inhaltsverzeichnis

1;Foreword;7
2;Preface;11
3;Contents;13
4;List of Contributors;19
5;Part I Theory and Modelling;22
5.1;1 From Quantum Models to Novel E.ects to New Applications: Theory of Nanotube Devices;23
5.1.1;1.1 Introduction: Classical vs. Quantum Modelling;23
5.1.2;1.2 Classical Terms: Weak Screening in 1D Systems;25
5.1.3;1.3 Quantum Terms. I. Quantum Capacitance;31
5.1.4;1.4 Quantum Terms. II. Spontaneous Symmetry Breaking;38
5.1.5;1.5 Quantum Terms. III. Band Structure Engineering;45
5.1.6;1.6 Novel Device Concepts: Metallic Field – E . ect Transistor (METFET);49
5.1.7;References;57
5.2;2 Symmetry Based Fundamentals of Carbon Nanotubes;60
5.2.1;2.1 Introduction;60
5.2.2;2.2 Con.guration and Symmetry;61
5.2.3;2.3 Symmetry Based Band Calculations;68
5.2.4;2.4 Optical Absorption;79
5.2.5;2.5 Phonons;87
5.2.6;2.6 Symmetry Breaks Friction: Super-Slippery Walls;99
5.2.7;References;104
5.3;3 Elastic Continuum Models of Phonons in Carbon Nanotubes;108
5.3.1;3.1 Introduction;108
5.3.2;3.2 Acoustic Modes in Single Wall Nanotubes;109
5.3.3;3.3 Optical Modes in Multi-wall Nanotubes;121
5.3.4;3.4 Quantized Vibrational Modes in Hollow Spheres;127
5.3.5;3.5 Conclusions;128
5.3.6;References;128
6;Part II Synthesis and Characterization;130
6.1;4 Direct Growth of Single Walled Carbon Nanotubes on Flat Substrates for Nanoscale Electronic Applications;131
6.1.1;4.1 Introduction;131
6.1.2;4.2 Diameter Control;132
6.1.3;4.3 Orientation Control;136
6.1.4;4.4 Growth of Superlong and Well-Aligned SWNTs on a Flat Surface by the Fast- Heating Process;137
6.1.5;4.5 Growth Mechanism;140
6.1.6;4.6 Advantages of Long and Oriented Nanotubes for Device Applications;147
6.1.7;4.7 Summary;147
6.1.8;References;148
6.2;5 Nano-Peapods Encapsulating Fullerenes;151
6.2.1;5.1 Introduction;151
6.2.2;5.2 High-Yield Synthesis of Nano-Peapods;152
6.2.3;5.3 Packing Alignment of the Fullerenes Inside SWNTs;155
6.2.4;5.4 Electronic Structures of Nano-Peapods;157
6.2.5;5.5 Transport Properties of Nano-Peapods;160
6.2.6;5.6 Nano-Peapod as a Sample Cell at Nanometer Scale;162
6.2.7;5.7 Peapod as a Nano-Reactor ;163
6.2.8;5.8 Conclusions;166
6.2.9;References;166
6.3;6 The Selective Chemistry of Single Walled Carbon Nanotubes;169
6.3.1;6.1 Introduction: Advances in Carbon Nanotube Characterization;169
6.3.2;6.2 Selective Covalent Chemistry of Single- Walled Carbon Nanotubes;171
6.3.3;6.3 Selective Non-covalent Chemistry: Charge Transfer;182
6.3.4;6.4 Selective Non-covalent Chemistry: Solvatochromism;188
6.3.5;References;195
7;Part III Optical Spectroscopy;199
7.1;7 Fluorescence Spectroscopy of Single- Walled Carbon Nanotubes;200
7.1.1;7.1 Introduction;200
7.1.2;7.2 Observation of Photoluminescence;202
7.1.3;7.3 Deciphering the (n, m) Spectral Assignment;203
7.1.4;7.4 Implications of the Spectral Assignment;204
7.1.5;7.5 Transition Line Shapes and Single- Nanotube Optical Spectroscopy;209
7.1.6;7.6 Influence of Sample Preparation on Optical Spectra;211
7.1.7;7.7 Spectro.uorimetric Sample Analysis;212
7.1.8;7.8 Detection, Imaging, and Electroluminescence;215
7.1.9;7.9 Conclusions;217
7.1.10;References;217
7.2;8 The Raman Response of Double Wall Carbon Nanotubes;220
7.2.1;8.1 Introduction;220
7.2.2;8.2 Experimental;222
7.2.3;8.3 Results and Discussion;223
7.2.4;References;239
8;Part IV Transport and Electromechanical Applications;242
8.1;9 Carbon Nanotube Electronics and Optoelectronics;243
8.1.1;9.1 Introduction;243
8.1.2;9.2 Electronic Structure and Electrical Properties of Carbon Nanotubes;244
8.1.3;9.3 Potential and Realized Advantages of Carbon Nanotubes in Electronics Applications;246
8.1.4;9.4 Fabrication and Performance of Carbon Nanotube Field- E . ect Transistors;247
8.1.5;9.5 Carbon Nanotube Transistor Operation in Terms of a Schottky Barrier Model;251
8.1.6;9.6 The Role of Nanotube Diameter and Gate Oxide Thickness;253
8.1.7;9.7 Environmental In.uences on the Performance of CNT- FETs;255
8.1.8;9.8 Scaling of CNT-FETs;257
8.1.9;9.9 Prototype Carbon Nanotube Circuits;258
8.1.10;9.10 Optoelectronic Properties of Carbon Nanotubes;260
8.1.11;9.11 Summary;264
8.1.12;References;265
8.2;10 Carbon Nanotube–Biomolecule Interactions: Applications in Carbon Nanotube Separation and Biosensing;268
8.2.1;10.1 Introduction;268
8.2.2;10.2 DNA-Assisted Dispersion and Separation of Carbon Nanotubes;269
8.2.3;10.3 Separation of Carbon Nanotubes Dispersed by Non- ionic Surfactant;273
8.2.4;10.4 Structure and Electrostatics of the DNA/ CNT Hybrid Material;277
8.2.5;10.5 E.ects of Protein Adsorption on the Electronic Properties of Single Walled Carbon Nanotubes;282
8.2.6;References;285
8.3;11 Electrical and Mechanical Properties of Nanotubes Determined Using In- situ TEM Probes;287
8.3.1;11.1 Introduction;287
8.3.2;11.2 Studies of Carbon Nanotubes;292
8.3.3;11.3 Studies of Boron Nitride Nanotubes;313
8.3.4;11.4 Electron Field Emission from BN Nanotubes;314
8.3.5;11.5 Electrical Breakdown and Conduction of BN Nanotubes;316
8.3.6;References;317
8.4;12 Nanomanipulator Measurements of the Mechanics of Nanostructures and Nanocomposites;321
8.4.1;12.1 Introduction;321
8.4.2;12.2 Nanomanipulators;323
8.4.3;12.3 Nanomanipulator-Based Mechanics Measurements;332
8.4.4;12.4 Summary and Future Directions;347
8.4.5;References;349
9;Color Plates;352
10;Index;358

Leseproben

1 From Quantum Models to Novel Effects to New Applications: Theory of Nanotube Devices by S.V. Rotkin (p. 3-4)

Classical and quantum effects in the physics of nanotube devices are presented. In particular, weak screening in one–dimensional systems is shown to essentially modify textbook theory of field–effect devices and lead to an interesting dependence of the device characteristics on geometrical factors.

The capacitance of a nanoscale device has two main components: a classical geometric capacitance and a quantum term. The latter is related to a finite density of states of the nanosystem. Derivation of this density of states in the presence of external perturbations is a difficult task. We present some examples of the modification of the nanotube bandstructure by external perturbations.

Electric fields can be used for band gap engineering in nanotubes, which may be translated into the device function. The concept of the Metallic Field–Effect Transistor is proposed. This device shows, at least theoretically, metallic conductance in the ON state and insulating behavior in the OFF state, which may be important for applications.

1.1 Introduction: Classical vs. Quantum Modelling

One of the expectations of nanotechnology, an area foreseen by Dr. Richard P. Feynman in 1959 [1], is that we may be able to access quantum properties of materials, which may ultimately lead to new applications and new device operations, which are not possible at the macroscale. To enable this new technology a theory that can make both qualitative and quantitative predictions is needed, whether it be a classical or quantum theory or a combination of both. In this chapter we give a few examples and present the quantum vs. the classical approach using recent results from our modelling of nanotube based devices.

Carbon nanotubes (NTs), discovered in 1991 [2], nowadays represent a new class of electronic materials. The electronic properties of NTs depend on their symmetry [3]. This is not unusual but for a single–wall nanotube (SWNT) there are just a couple of geometrical parameters: a curvature radius, R, and a helicity angle (the measure of chirality of the SWNT lattice), which solely define transport [4], optical [5] and even, to some extent, chemical [6,7] properties of a SWNT.

Knowledge of these two parameters will allow us to divide all possible NTs into several distinct classes. Two thirds of SWNTs have a forbidden band gap, which makes them semiconductors. The band gaps of the semiconductor SWNTs are in the optical region (near–IR/visible), depending on the value of R. The experimental fact that, over a wide range of R, the energy gap is proportional to the curvature, 1/R [5], is a clear manifestation of a simple quantum effect of a space quantization of an electron. When winding around the tube circumference, the electron acquires a phase. After making a full turn the phase has to be 2p, which results in a so–called quantization condition.

The quantization energy sets the separation between the conduction and valence bands, and therefore the optical gap. In a similar way, as the atomic size (atomic number) of an element in the Periodic Table solely defines the properties of the substance, the curvature radius and the helicity angle of a SWNT define its electronic material properties. One third of SWNTs are either metals or narrow gap semiconductors (often called “quasi–metals” in NT literature). The difference between the gap size in the last two SWNT classes appears in the second order of the curvature, 1/R2. The gap in the quasi–metallic SWNT scales as ?/R2, where ?  2.7 eV is the hopping integral which gives the NT energy scale. In the same second order of the curvature, 1/R2, the first SWNT class (semiconductors) splits into two sub–classes by their chirality. All this constitutes a specific “Periodic Table” of nanotubes.

The other important property of nanotubes relates to their third dimension: we have already considered the radius and chirality of the tube but not the length. Recent success in NT synthesis (see also [8]) allowed experimental study of NTs with R ~ 1 nm and lengths of about several hundreds to thousands of microns, which implies an aspect ratio of 1:100,000 and greater. Certainly, this object must show physics similar to the physics of a one– dimensional (1D) wire, for example, a weak screening. Below we demonstrate that the weak 1D screening properties of NTs have important consequences for electronic devices.