Nanowires get into the groove

August 23, 2011

Growing up is not easy, especially for tiny nanowires: With no support or guidance, nanowires become unruly, making it difficult to harness their full potential as effective semiconductors. Prof. Ernesto Joselevich of the Weizmann Institute's Chemistry Faculty has found a way to grow semiconductor nanowires out, not up, on a surface, providing, for the first time, the much-needed guidance to produce relatively long, orderly, aligned structures. Since semiconductors with controlled structures are at the core of the most advanced technologies, this new research will hopefully enable the production of semiconductor nanostructures with enhanced electronic and optical properties, suitable for a wide range of applications including LEDs, lasers, information storage media, transistors, computers, photovoltaics and more.

Joselevich, Ph.D. student David Tsivion and postdoctoral fellow Mark Schvartzman of the Materials and Interfaces Department grew nanowires made of gallium nitride (GaN) using a method that usually produces vertical nanowires with excellent optical and electronic properties. These vertical wires only become unruly once they are harvested and assembled into arrays. To bypass this problem, the scientists used sapphire as a base on which to grow the nanowires. But rather than growing them on a smooth surface, deliberately cut the sapphire along different planes of the crystal, resulting in various surface patterns including 'steps' of nano-meter dimensions between the different planes of the crystal, as well as accordion-like, V-shaped grooves.

Their results, recently published in Science, show that surface steps and grooves have a strong guiding effect, coaxing the nanowires to grow horizontally along their edges or within the grooves and producing well-aligned, millimeter-long nanowire arrays. In contrast, current methods of assembling nanowires horizontally on smooth surfaces result in disorderly nanowires only micrometers in length with subpar properties.

Joselevich: 'It was surprising to discover that the optical and electronic properties of our nanowires were just as good - if not better - than those grown vertically, because growing semiconductors on a surface usually introduces defects that degrade their quality.'

Although it is still not fully clear how a method that normally produces vertical nanowires works to create horizontal growth in the new study, Joselevich and his team have managed to combine, in a single step, the synthesis and assembly of well-structured nanowires with unique properties suitable for a wide range of applications, by simply getting them 'into the groove.' ?

###

The Weizmann Institute of Science in Rehovot, Israel, is one of the world's top-ranking multidisciplinary research institutions. Noted for its wide-ranging exploration of the natural and exact sciences, the Institute is home to 2,700 scientists, students, technicians and supporting staff. Institute research efforts include the search for new ways of fighting disease and hunger, examining leading questions in mathematics and computer science, probing the physics of matter and the universe, creating novel materials and developing new strategies for protecting the environment.

Weizmann Institute of Science

Handbook of Nanophysics: Nanotubes and Nanowires
by Klaus D. Sattler (Editor)

Intensive research on fullerenes, nanoparticles, and quantum dots in the 1990s led to interest in nanotubes and nanowires in subsequent years. Handbook of Nanophysics: Nanotubes and Nanowires focuses on the fundamental physics and latest applications of these important nanoscale materials and structures. Each peer-reviewed chapter contains a broad-based introduction and enhances understanding of the state-of-the-art scientific content through fundamental equations and illustrations, some in color. This volume first covers key aspects of carbon nanotubes, including quantum and electron transport, isotope engineering, and fluid flow, before exploring inorganic nanotubes, such as spinel oxide nanotubes, magnetic nanotubes, and self-assembled peptide nanostructures. It then focuses on...

Inorganic Nanowires: Applications, Properties, and Characterization (Nanomaterials and their Applications)
by M. Meyyappan (Author), Mahendra K. Sunkara (Author)

Advances in nanofabrication, characterization tools, and the drive to commercialize nanotechnology products have contributed to the significant increase in research on inorganic nanowires (INWs). Yet few if any books provide the necessary comprehensive and coherent account of this important evolution. Presenting essential information on both popular and emerging varieties, Inorganic Nanowires: Applications, Properties, and Characterization addresses the growth, characterization, and properties of nanowires. Author Meyyappan is the director and senior scientist at Ames Center for Nanotechnology and a renowned leader in nanoscience and technology, and Sunkara is also a major contributor to nanowire literature. Their cutting-edge work is the basis for much of the current understanding in...

Nanowires and Nanobelts: Materials, Properties and Devices (2 Volumes)
by Zhong Lin Wang (Editor)

This two volume reference, Nanowires and Nanobelts: Materials, Properties and Devices, provides a comprehensive introduction to the field and reviews the current state of the research.
Volume 1, Metal and Semiconductor Nanowires covers a wide range of materials systems, from noble metals (such as Au, Ag, Cu), single element semiconductors (such as Si and Ge), compound semiconductors (such as InP, CdS and GaAs as well as heterostructures), nitrides (such as GaN and Si3N4) to carbides (such as SiC). The objective of this volume is to cover the synthesis, properties and device applications of nanowires based on metal and semiconductor materials. The volume starts with a review on novel electronic and optical nanodevices, nanosensors and logic circuits that have been built using...

Nanowires and Nanobelts: Materials, Properties and Devices: Volume 1: Metal and Semiconductor Nanowires
by Zhong Lin Wang (Editor)

Volume 1, Metal and Semiconductor Nanowires covers a wide range of materials systems, from noble metals (such as Au, Ag, Cu), single element semiconductors (such as Si and Ge), compound semiconductors (such as InP, CdS and GaAs as well as heterostructures), nitrides (such as GaN and Si3N4) to carbides (such as SiC). The objective of this volume is to cover the synthesis, properties and device applications of nanowires based on metal and semiconductor materials. The volume starts with a review on novel electronic and optical nanodevices, nanosensors and logic circuits that have been built using individual nanowires as building blocks. Then, the theoretical background for electrical properties and mechanical properties of nanowires is given. The molecular nanowires, their quantized...

Nanotubes and Nanowires (Selected Topics in Electronics and Systems)
by Peter John Burke (Author), Peter John Burke (Editor)

The field of nanotubes and nanowires is evolving at a rapid pace, with many potential applications in electronics, optics, and sensors, to name a few. In this book, various prominent researchers summarize our current understanding of these new materials systems, as well as some of these potential applications. A snapshot of the state-of-the-art in the field of nanowires and nanotubes, the contributions give an instructive mix of experimental, theoretical, and visionary material to give the reader an indication of where the field is now, and where it is going.

Nanoelectronics: Nanowires, Molecular Electronics, and Nanodevices
by Krzysztof Iniewski (Author)

The latest advances in nanoelectronics This definitive volume addresses the state of the art in nanoelectronics, covering nanowires, molecular electronics, and nanodevices. Written by global experts in the field, Nanoelectronics discusses cutting-edge techniques and emerging materials, such as carbon nanotubes and quantum dots. This pioneering work offers a comprehensive survey of nanofabrication options for use in next-generation technologies. Nanoelectronics covers: Electrical properties of metallic nanowires Electromigration defect nucleation in damascene copper interconnect lines Carbon nanotube interconnects in CMOS integrated circuits Printed organic electronics One-dimensional nanostructure-enabled chemical sensing Cross-section fabrication and...

Nanotubes and Nanowires (RSC Nanoscience & Nanotechnology)
by C N Ram Rao (Author), A Govindaraj (Author), Harry Kroto (Series Editor), Paul O'Brien (Series Editor), Harold Craighead (Series Editor)

Research and literature on nanomaterials has exploded in volume in recent years. Nanotubes (both of carbon and inorganic materials) can be made in a variety of ways. Many of these properties, such as high mechanical strength and interesting electronic properties relate directly to potential applications. Nanowires have been made from a vast array of inorganic materials and provide great scope for further research into their properties and possible applications. This book provides a comprehensive and up-to-date survey of the research areas of carbon nanotubes, inorganic nanotubes and nanowires including: synthesis; characterisation; properties; applications. This fully revised and updated edition includes an extensive list of references and is ideal both for graduates needing an...

Nanotubes and Nanowires (Proceedings of SPIE)
by Akhlesh Lakhtakia (Editor), Sergey Maksimenko (Editor)

Molecular Nanowires and Other Quantum Objects (Nato Science Series II: (closed))
by Alexandre S. Alexandrov (Editor), Jure Demsar (Editor), Igor K. Yanson (Editor)

There is a growing understanding that the progress of the conventional silicon technology will reach its physical, engineering and economic limits in about a decade. What will take us beyond 2010 are new molecular and other nanotechnologies that require the efforts of trans-disciplinary teams of physicists, quantum chemists, material and computer scientists, and engineers. This volume represents a unique collection of interdisciplinary review and original papers by experts in molecular nanowires, carbon nanotubes, mesoscopic super- and semiconductors, and theorists in the field of strongly correlated electrons and phonons. Topics include molecular nanojunctions and electronics, mesoscale semiconductors and superconductors, carbon nanotubes, low dimensional conductors, polarons and...

Quantum Dots and Nanowires
by Supriyo Bandyopadhyay and Hari Singh Nalwa (Author), Supriyo Bandyopadhyay (Editor), Hari Singh-Nalwa (Editor)

Quantum Dots and Nanowires provides coverage on various emerging aspects of quantum dots and nanowires. This book covers recent advances in physical and chemical synthetic approaches, processing and fabrication of semiconductor quantum-dot arrays, superlattices, self-assemblies, nanowires, nanotubes and nanobelts, computational modeling approaches, spectroscopic characterization, their unique electrical, optical, magnetic and physical properties associated with size effect, transport phenomena, quantum computing, and other potential applications. An essential resource for scientists, researchers, upper-level undergraduate and graduate students, and college and university professors working in the field of electrical and electronic engineering, materials science, solids tate physics,...