Nanowires_1

Nanowires Nanowires Edited by Paola Prete Intech IV Published by Intech Intech Olajnica 19/2, 32000 Vukovar, Croatia Abstracting and non-profit use of the material is permitted with credit to the source. Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published articles. Publisher assumes no responsibility liability for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained inside. After this work has been published by the Intech, authors have the right to republish it, in whole or part, in any publication of which they are an author or editor, and the make other personal use of the work. © 2010 Intech Free online edition of this book you can find under www.sciyo.com Additional copies can be obtained from: publication@sciyo.com First published March 2010 Printed in India Technical Editor: Teodora Smiljanic Cover designed by Dino Smrekar Nanowires, Edited by Paola Prete p. cm. ISBN 978-953-7619-79-4 Preface The study of quasi 1-dimensional (1d) semiconductor nano-crystals (so-called nanowires) represents the forefront of today’s solid state physics and technology. Due to their many unique and fascinating physical properties (among others, superior mechanic toughness, higher carrier mobility and luminescence efficiency, and lowered lasing threshold), these systems are increasingly being considered as fundamental ‘building blocks’ for the realization of entirely new classes of nano-scale devices and circuits, with applications stretching from photonics to nano-electronics, and from sensors to photovoltaics. Free-standing semiconductor nanowires have been used to fabricate nanometer-scale field-effect transistors (FETs), bipolar junction transistors, and light-emitting diodes, nano-scale lasers, complementary inverters, complex logic gates, gas sensors, nano-resonators, nano-generators and nano-photovoltaic devices. Since the very first pioneering works carried out by K. Hiruma in Japan in the mid 90’s, and by C.M. Lieber, P. Yang, and Z.L. Wang in USA by the end of 90’s, successful demonstration of such a large variety of functional devices has lead to a rapidly growing interest in nanowire researches around the world and to a steep increase in the number of annual publications (the ISI-Thomson ‘Web of Science’ database reports over 800 papers published in the year 2009 under the combined keywords ‘nanowires & semiconductors’). Such a breathtaking pace of research has allowed to explore the field in several directions within just a few years. The synthesis of free-standing nanowire structures now involves a large variety of methods and materials, including elemental and compound (both binary and multinary) semiconductors as well as complex modulated nanostructures. A seemingly vast amount of studies is being dedicated to understanding the physical-chemical and structural properties of these quasi 1d systems, and how they relate to the various synthesis mechanisms and parameters; this is being increasingly realized through the use of advanced nano-scale characterization tools and methods either directly on as-synthesized nanostructures or on nanowire-based devices. Still, a full understanding of nanowire physics cannot be achieved without a combination of these advanced characterizations with first principles (ab initio) calculations and methods to model their nano-scale characteristics and/or device performances. This volume is intended to orient the reader in the fast developing field of semiconductor nanowires, by providing a series of self-contained monographs focusing on various nanowire-related topics. Each monograph serves as a short review of previous results in the literature and description of methods used in the field, as well as a summary of ... - tailieumienphi.vn