nanomaterials and nanotechnology Collection of Selected Papers | 2013 | issn 1847-9804 © Vasil Vasilev/Shutterstock © Vasil Editor-in-Chief Paola Prete Institute for Microelectronics and Microsystems, National Research Council, Lecce, Italy Editorial Board C. N. R. Rao Fellow of the Royal Society, National Research Professor, Linus Pauling Research Professor and President of Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India Toshiaki Enoki Tokyo Institute of Technology, Japan Stephen O’Brien Department of Chemistry, The City College of New York, USA Juan Ramon Morante Catalonia Institute for Energy Research and University of Barcelona, Spain Stephen Pearton Department of Material Science and Engineering, University of Florida, USA Wolfgang Richter University of Rome Tor Vergata, Italy and Technischen Universität Berlin, Germany Federico Rosei Institut National de la Recherche Scientifique, Universite du Quebec, Varennes, Canada Jonathan E. Spanier Department of Materials Science and Engineering, Drexel University, Philadelphia, USA Leander Tapfer Technical Unit of Materials Technologies Brindisi, ENEA, Italy Reshef Tenne Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel Fabrice Vallee CNRS and Université Claude Bernard Lyon, France Nanomater. nanotechnol., 2013, Collection of Selected Papers free online editions of InTech Books and Journals can be found at www.intechopen.com Nanomaterials and Nanotechnology Collection of Selected Papers, 2013 Abstracted/Indexed in IET Inspec, Ulrich’s Periodical Directory, Scirus, EBSCO - A-to-Z, WorldCat, BASE - Bielefeld Academic Search Engine, DOAJ - Directory of Open Access Journals, Electronic Journals Library, Google Scholar, CAS - Chemical Abstracts Service, Hrcak Published by InTech Janeza Trdine 9, 51000 Rijeka, Croatia Identification Statement Online ISSN 1847-9804 Abbreviated key title: Nanomater. nanotechnol. Start year: 2011 Copyright ∂ 2013 InTech All articles are Open Access articles distributed under the Creative Commons Non Commercial Share Alike Attribution 3.0 license, which permits to copy, distribute, transmit, and adapt the work in any medium, so long as the original work is properly cited. After this work has been published by InTech, authors have the right to republish it, in whole or part, in any publication of which they are the author, and to make other personal use of the work. Any republication, referencing or personal use of the work must explicitly identify the original source. As for readers, this license allows users to download, copy and build upon published articles as long as the author and publisher are properly credited. Notice Statements and opinions expressed in the papers 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. The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained in the journal. Cover Image Copyright 2011. Used under license from Shutterstock.com Contact You can contact us at [email protected] A free online edition of this journal is available at www.intechopen.com Nanomater. nanotechnol., 2013, Collection of Selected Papers Contents Wide Bandgap Semiconductor One-Dimensional Nanostructures for Applications in Nanoelectronics and Nanosensors 1 Stephen J. Pearton and Fan Ren Assembled Nanostructured Architectures Studied by Grazing Incidence X-Ray Scattering 17 Davide Altamura, Teresa Sibillano, Dritan Siliqi, Liberato De Caro and Cinzia Giannini Numerical Techniques for the Analysis of Charge Transport and Electrodynamics in Graphene Nanoribbons 41 Luca Pierantoni and Davide Mencarelli Synthetic Aspects and Selected Properties of Graphene 49 H. S. S. Ramakrishna Matte, K. S. Subrahmanyam and C. N. R. Rao Complex Nanostructures by Pulsed Droplet Epitaxy 61 Stefano Sanguinetti, Claudio Somaschini, Sergio Bietti and Noboyuki Koguchi Magnetic Properties of Fe and Ni Doped SnO2 Nanoparticles 65 Aditya Sharma, Mayora Varshney, Shalendra Kumar, K. D. Verma and Ravi Kumar ARTICLE Nanomaterials and Nanotechnology Wide Bandgap Semiconductor One-Dimensional Nanostructures for Applications in Nanoelectronics and Nanosensors Invited Review Article Stephen J. Pearton1,* and Fan Ren2 1 Department of Materials Science and Engineering, University of Florida, Gainesville FL 32611 USA 2 Department of Chemical Engineering, University of Florida, Gainesville FL 32611 USA * Corresponding author E-mail: [email protected] Received 21 November 2012; Accepted 15 January 2013 © 2013 Pearton and Ren; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Wide bandgap semiconductor ZnO, GaN and materials for gas detection [1‐5]. One‐dimensional (1D) InN nanowires have displayed the ability to detect many nanostructures, such as nanowires, nanorods and types of gases and biological and chemical species of nanobelts, are particularly suited for chemical sensing interest. In this review, we give some recent examples of due to their large surface‐to‐volume ratio [6‐11]. In terms using these nanowires for applications in pH sensing, of material selection, wide band‐gap semiconductors are glucose detection and hydrogen detection at ppm levels. ideal for gas sensing, having numerous advantageous The wide bandgap materials offer advantages in terms of properties, including an ability to operate at high sensing because of their tolerance to high temperatures, temperatures (or alternatively, a low leakage current at environmental stability and the fact that they are usually room temperature), radiation and environmental piezoelectric. They are also readily integrated with stability, and mechanical robustness. The literature of wireless communication circuitry for data transmission. more than a decade of research indicates an improvement in consistent growth methods and the potential for the Keywords GaN, ZnO, InN immediate industrial use of 1D semiconductor nanostructures. Specific semiconductor materials including III‐nitrides such as GaN [12‐13] and InN [14‐ 1. Introduction 16], metal oxides including ZnO and SnO2 [17‐18], and high‐temperature materials such as SiC [19] have seen the The explosion of interest in nanoscience, coupled with greatest interest for chemical gas sensing applications, growing demand for reliable, low‐power chemical chiefly for the detection of H2, O2, NH3 and ethanol. There sensors for a wide variety of industrial applications, has is also interest in applying these to biomarker detection led to a surge in the development of nanostructured [21‐30]. www.intechopen.com Stephen J. PeartonNanomater. and Fan nanotechnol., Ren: Wide Bandgap 2013, Collection Semiconductor of Selected One-Dimensional Papers, 1-16 1 Nanostructures for Applications in Nanoelectronics and Nanosensors There is a strong need for mobile, accurate, low power There are many potential applications for wide bandgap sensors that can be used in applications such as personal semiconductor nanowire devices because of their health monitoring, security, perimeter defence, food improved carrier confinement over their thin film spoilage, the monitoring of nuclear materials and gas counterparts. For GaN nanowires, there are possible leaks. Currently, many of these applications are applications in low power and high density field‐effect monitored by lab‐based methods, such as enzyme‐linked transistors (FETs), solar cells, terahertz emitters and UV immunosorbent assay (ELISA), particle‐based flow detectors. The high surface‐to‐volume ratio of nanowires cytometric assays or electrochemical measurements. means that if their surfaces are sensitive to external These methods have impressive sensitivity and stimuli or can be functionalized to be sensitive to specific reproducibility. However, many of the applications chemicals or biogens, then they are likely to be attractive mentioned above would benefit from the ability to have for gas and chemical sensor arrays. ZnO is a piezoelectric, sensing capabilities in a broader range of environments. transparent, wide bandgap semiconductor used in surface To move these out of lab environment requires acoustic wave devices. The bandgap can be increased by miniaturization and new approaches to solving power Mg doping. ZnO has been effectively used as a gas sensor consumption and hand‐held capability. In particular, it material based on the near‐surface modification of charge would be good to have a wireless capability for sending distribution with certain surface‐absorbed species. In sensor data to a remote monitoring site and also to addition, it is attractive for biosensors given that Zn and miniaturize the sensors so as to allow for truly mobile or Mg are essential elements for neurotransmitter production long‐term remote monitoring. The techniques mentioned and enzyme functionality. above all have significant limitations in terms of using them outside of controlled lab environments, both in In this review, we discuss the progress of nitride and terms of the size of the components and power oxide semiconductor nanostructures for nanoelectronic requirements. For long‐term monitoring applications,