Inorganic Nanostructures E-Book

Petra Reinke

• Herausgeber: Wiley-VCH
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 374

Veröffentlichungsjahr: 2012

Beschreibung

This monograph for young researchers and professionals looking for a comprehensive reference offers an advanced treatment of the topic that extends beyond an introductory work.
As such, it systematically covers the inorganic nanostructures in the breadth needed, while presenting them together with the surface science tools used to characterize them, such as electron spectroscopy and scanning probe techniques. The unique challenges in the fabrication of nanostructures are illustrated, and set into context of controlling structure, dimensionality and electronic properties.

Leseprobe

Contents

Preface

Chapter 1: Dimensions and Surfaces – an Introduction

1.1 Size, Dimensionality, and Confinement

1.2 Synthesis of Nanostructures: Fundamental Surface Processes and Reactions

1.3 Closing Remarks

Chapter 2: Experimental Techniques for Nanoscale Materials Analysis

2.1 Scanning Probe Microscopy

2.2 Photoelectron Spectroscopy and Electron Spectroscopy Techniques

2.3 Closing Remarks

Chapter 3: Semiconductor Nanowires

3.1 Nanowire Growth

3.2 Vapor–Liquid–Solid and Vapor–Solid–Solid Growth

3.3 Nanowire Crystallography – Wire Structure

3.4 Horizontal Nanowires

3.5 Controlling the Electronic Properties of Semiconductor Nanowires

3.6 Closing Remarks

Chapter 4: Metal Clusters

4.1 Cluster–Surface Interaction

4.2 Synthesis of Metal Clusters

4.3 Geometry of Clusters

4.4 Closing Remarks

Chapter 5: Quantum Dots

5.1 Size and Shape in Quantum Dots

5.2 Band Gap, Size, and Absorption Edge

5.3 Synthesis of QDs

5.4 Superlattices Made of QDs

5.5 Closing Remarks

Chapter 6: Pure Carbon Materials

6.1 Carbonaceous Materials and Bonding

6.2 Low-Dimensional Carbon Nanostructures

6.3 Electronic and Geometric Structure: Graphene and Carbon Nanotubes

6.4 Graphene – the Electron as a Massless Dirac Fermion

6.5 Synthesis of Graphene

6.6 Closing Remarks

Chapter 7: A Few Applications of Inorganic Nanostructures

7.1 Single Electron Transistor

7.2 Sensing with Graphene and Carbon Nanotubes

7.3 Quantum Dots, Rods, and Nanotubes in Photovoltaics

References

Index

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The Author

Prof. Petra Reinke

University of Virginia

Dept. of Mat. Science and Eng.

395, McCormick Road

Charlottesville, VA 22904

USA

All books published by Wiley-VCH are carefully produced. Nevertheless, authors, editors, and publisher do not warrant the information contained in these books, including this book, to be free of errors. Readers are advised to keep in mind that statements, data, illustrations, procedural details or other items may inadvertently be inaccurate.

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The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available on the Internet at <http://dnb.d-nb.de>.

© 2012 Wiley-VCH Verlag & Co. KGaA, Boschstr. 12, 69469 Weinheim, Germany

All rights reserved (including those of translation into other languages). No part of this book may be reproduced in any form – by photoprinting, microfilm, or any other means – nor transmitted or translated into a machine language without written permission from the publishers. Registered names, trademarks, etc. used in this book, even when not specifically marked as such, are not to be considered unprotected by law.

Cover Design Adam-Design, Weinheim, Germany

Print ISBN:978-3-527-40925-9

ePDF ISBN:978-3-527-64593-0

oBook ISBN:978-3-527-64590-9

ePub ISBN:978-3-527-64592-3

Mobi ISBN:978-3-527-64591-6

For Mieko

Preface

Writing this book was an adventure - sometimes more like a rollercoaster ride, often peppered with surprising discoveries, and infused with many fascinating ideas and technological developments. Nanoscience has in the last decade evolved into one of the fastest paced areas in science and has had an impact on nearly every discipline including materials science, medicine, physics, chemistry, and biology. It is a truly interdisciplinary endeavor, which is not only evident in the pertinent literature but also increasingly visible in the classroom. The number of publications in many areas of nanoscience and -technology is increasing rapidly, one recent example is the discovery of graphene: in the year 2000 the number of publications on graphene was small, just a few people growing “dirt” on metal surfaces, but with the recognition of its extraordinary electronic properties, interest in this unique material exploded. By now it has become nearly impossible to even keep up with the literature. But graphene is also an old material: the first attempts to understand bonding in graphite used graphene as a model system without realizing that it is indeed possible to make these single layers. Understanding of properties combined with the newly found ability to synthesize the material created the “perfect storm” a few years ago. The present book ventures to illustrate this correlation: how can we make a material and how can we understand and then control its properties? What can we learn by understanding synthesis, how can we achieve the superb control over structure, geometry, composition which is needed to make fully functional nanostructures? I hope it will guide students and researchers alike on a journey into a wonderful and ever expanding world of nano-materials.

A large project such as writing a book or conducting research cannot be done alone, and this is the place to thank everybody who has supported me throughout my career. As you might have guessed, the list is long, and today I limit myself to mention just a few, otherwise quite a few more pages would have to be added to this book. First and foremost my thanks go to my students, past and present, and those who share currently in the exciting exploration of surfaces and nanomaterials (and proofread several chapters) - you will find some of their work in the pages of this book and on the cover page. Their comments on my book manuscript and our discussions in the lab, office, classroom and during “boot-camp sessions” were (and are) instrumental in shaping my thoughts and ideas. Thanks to all my colleagues with whom I share discussions and thoughts on science and teaching and life, and those who proofread parts of this book - Archie Holmes, and Renee Diehl - your comments were critical to the development of my thoughts. I was fortunate to have in Bill Johnson a department chair who gave me the opportunity to develop and teach several courses on Nanoscience, which in the end culminated in the writing of this book.

Acknowledgements for Cover Art

All images displayed on the cover are STM (scanning tunneling microscopy) images taken by students in my research group. They illustrate their skill and dedication, and showcase some of the projects we have pursued in recent years.

Center image: Ge quantum dot (hut) grown by Stranski-Krastanov growth of Ge on the Si(100) surface. The QD was fabricated and recorded by Christopher A. Nolph in the framework of an NSF award by the Division of Materials Research (Electronic and Photonic Materials) award number DMR-0907234.

Image on left hand side (green): Surface of a fullerene layer - the spheres are individual fullerene molecules, which rotate at room temperature and therefore the individual atoms cannot be distinguished. The fullerene layer was deposited and imaged by Harmonie Sahalov. Her project was supported by NSF award number DMR-105808 (Division of Materials Research, Ceramics).

Center image - back panel (blue): This image shows the structures formed by Vanadium metal if it is deposited on a graphite surface at room temperature. The deposition and imaging were done by Wenjing Yin, and her project was supported by the Defense Microelectronics Agency under contract DMEA2-H94003-08-2-0803.

Image on right hand side (yellow): The surface depicted in this image is a Si(100)(2x1) reconstructed surface with mono-atomic Manganese wires, which run perpendicular to the Si-dimer rows. The work was done by Kiril R. Simov in the framework of NSF awards by the Division of Chemistry (Electrochemistry and Surface Chemistry) CHE-0828318, and Division of Materials Research (Electronic and Photonic Materials) DMR-0907234. This image is published in Simov, K. R., Nolph, C.A., and Reinke, P. (2012) Guided Self-assembly of Mn-Wires on the Si(100)2×1) Surface in J. Phys. Chem. C116, 1670. Reprinted with permission, copyright 2011 American Chemical Society.

Chapter 1

Dimensions and Surfaces – an Introduction

This first chapter can be seen as a warm-up: it will prepare our mental muscles to think about nanomaterials, and why they can be considered as a class of materials in their own right. We will introduce the concept of confinement and dimensionality and derive the density of states (DOS) for low-dimensional structures. After a discussion of electronic properties we will move on to a quite different area of research, and discuss fundamental processes at surfaces, which are rarely included in materials science or physics core classes, but are important for the understanding of many aspects of nanomaterial synthesis.

1.1 Size, Dimensionality, and Confinement

The nanosize regime is defined by the transition between the bulk and atom, and is characterized by a rapid change in material properties with size. Each set of properties (mechanical properties, geometric and electronic structure, magnetic and optical properties, and reactivity) is defined by characteristic length scales. If the size of the system approaches a characteristic length scale, the property in question will be modified dramatically as a function of size. The intimate link between size and material properties is one of the most intriguing aspects of nanoscience, and is at the core of the discipline. The control of size is therefore often the most important, and difficult, challenge in the synthesis of nanostructures.

The decrease in size of a nanostructure is accompanied by a rapid change in the volume-to-surface ratio of atoms: a cube with a side length of 1 mm contains about 2.5·1019 atoms, and the percentage of surface atoms is only 2·10−6; for a cube side length of 1 μm the percentage of surface atoms increases to 2·10−3; and for 1 nm side length, only one true volume atom remains, which is surrounded on all sides by other atoms. This shift from a volume–atom dominated structure, where the majority of atoms has fully saturated bonds, to a surface–atom dominated structure has rather dramatic consequences.

One of the best-known examples, which illustrates the impact of the change in the ratio of surface-to-volume atoms, is the observation of the reactivity of nanosize catalyst particles [1–3]. Catalysts are industrial materials, which are produced in very high volumes and used in nearly every chemical process. The role of a catalyst in a chemical reaction is to lower the activation energies in one or several of the reaction steps, and it can therefore increase yield, reaction speed, and selectivity. Most catalysts contain a relatively high percentage of expensive noble metals, and increasing catalyst efficiency through reduction of its size can thus greatly diminish costs, and at the same time very often boosts efficiency. The reactivity increase with decreasing particle size can be attributed to several size dependent factors: a proportional increase in the number of reactive surface atoms and sites, changes in the electronic structure, and differences in the geometric structure and curvature of the surface, which presents a larger concentration of highly active edge and kink sites. The underlying mechanism of a catalytic reaction is often complex, and cannot be attributed to a single factor such as larger surface area or modulation of the electronic structure. The study of catalysts and catalytic reactions is a highly active field of research, and depends on the improved comprehension of nanoparticle synthesis and properties.