We describe the production of hierarchical branched nanowire structures by the sequential seeding of multiple wire generations with metal nanoparticles. Such complex structures represent the next step in the study of functional nanowires, as they increase the potential functionality of nanostructures produced in a self-assembled way. It is possible, for example, to fabricate a variety of active heterostructure segments with different compositions and diameters within a single connected structure. The focus of this work is on epitaxial III-V semiconductor branched nanowire structures, with the two materials GaP and In As used as typical examples of branched structures with cubic (zinc blende) and hexagonal (wurtzite) crystal structures. The general morphology of these structures will be described, as well as the relationship between morphology and crystal structure.
Kimberly A.Dick is a PhD student in solidstate physics at Lund University in Sweden. She completed her undergraduate studies in chemical physics in Canada and the United States before moving to Sweden in 2003.
Her research focuses on the production and characterization of III–V nanowires and branched nanowire structures. Her particular interests are growth mechanisms involved in nanowire formation, materials interactions during vapor-phase epitaxial growth, and applications of complex branched structures. She received an MRS Graduate Student Silver Award in 2005.
Dick can be reached at Solid State Physics, Lund University, Box 118, SE 221 00 Lund, Sweden; tel. 46-46-222-9586, fax 46-46-222-3637, and firstname.lastname@example.org.
Knut Deppert is a professor at Lund University in Sweden.
He studied crystallography at Humboldt University in Berlin, where he obtained his PhD degree in 1985. As a postdoctoral researcher, he worked on growth of crystal structures for optoelectronic devices.
At Lund University, his research centers on the application of aerosol methods to generate novel nanomaterials and nanodevices, in particular, sizeselected semiconductor nanoparticles; tailored pattering with nanoparticles; and the creation of one-dimensional semiconductor structures such as nanowires and nanotrees. He is also director of the university's education program on nanoscience and nanotechnology.
Deppert can be reached at Solid State Physics, Lund University, Box 118, SE 221 00 Lund, Sweden' tel.46-46-222-9520, fax 46-46-222-3637, and email@example.com.
Lisa S. Karlsson is a PhD student in the Division of Polymer and Materials Chemistry at Lund University, Sweden, and is active at the National Center for High-Resolution Electron Microscopy (nCHREM).
Karlsson's work is centered on the characterization of nanoparticle and nanowire structures by transmission electron microscopy, in close collaboration with the Solid State Physics research group at LundUniversity. Karlsson has been involved in characterization of metal, alloy, and core–shell aerosol nanoparticles produced by an evaporation/condensation technique. Recently, her focus has been on the crystallography of III–V nanowires and nanotrees with detailed characterization on the atomic scale.
Karlsson can be reached at Polymer and Materials Chemistry, Lund University, Box 124, SE 221 00 Lund, Swedenl tel. 46-46-222-8232, fax 46-46-222-4112, and firstname.lastname@example.org
Magnus W. Larsson is a final-year PhD student in the Division of Polymer and Materials Chemistry at Lund University, Sweden, and is active at the National Center for High-Resolution Electron Microscopy (nCHREM).
He holds an MSc degree in chemical engineering from Lund University.
Larsson's research is focused on transmission electron micros copy of semiconductor nanowires, working with high-resolution HAADF-STEM imaging and in situ techniques such as TEM-STM and high-temperature micros copy. His other research interests include photovoltaics and electrochemical solar cells, fuel cells, and hydrogen energy systems.
Larsson can be reached at Polymer an Materials Chemistry,Lund University, Box 124, SE 221 00 Lund, Swedenl tel. 46-46-222-8112, fax 46-46-222-4112, and e-mail email@example.com
Werner Seifert is a professor of solid-state physics at Lund University, Sweden. He holds Dr. rer. nat. and Dr. sc. nat. degrees from the University of Leipzig, Germany.
Seifert worked on the optimization of CVD for LED applications at Werk fur Fernsehelektronik, Berlin. He was a docent for solid-state chemistry in 1985 and has been at Lund University since 1991.
In 1997, Seifert briefly headed an epitaxy group at the University of California, Santa Barbara. The group focused on the growth and characterization of GaInN nanostructures. His current research interests are epitaxy of semiconductor compounds and in situ growth and self-organization of nanostructures.
Seifert can be reached at Solid State Physics, Lund University, Box 118, SE 221 00 Lund, Sweden; tel. 46-46-222-7671, fax 46-46-222-3637, and firstname.lastname@example.org.
L. Reine Wallenberg is a Professor of solid-state chemistry at Lund University in Sweden, where he has been since 2000. He also is the director of the National Center for High-Resolution Electron Microscopy (nCHREM) and one of the founders of Lund's Nanometer Structure Consortium.
He received his PhD degree from Lund in 1987 on the subject of nanoparticles and electron micros copy. After research visits at Arizona State University, Australian National University, and the Institute for Scientific and Industrial Research in Osaka, he joined the faculty of Lund.
His research interests include nanowires and nanoparticles, catalysts, mesoporous materials, and electron microscopy techniques for inorganic and biological materials.
Wallenberg can be reached at Polymer and Materials Chemistry, Lund University, Box 124, SE 221 00 Lund, Sweden; tel. 46-46-222-8233, fax 46-46-222-4112, and e-mailreine.wallenberg@ polymat.lth.se
Lars Samuelson is a Professor of solid-state physics at Lund University in Sweden. He is also the director of the Nanometer Structure Consortium, started in 1988, which is today the primary center for nanoscience in Sweden. Samuelson is the leader of a major European R&D project called NODE (Nanowire- Based One-Dimensional Electronics), with participation by leading European electronics industries, research institutes, and academic research teams.
Samuelson is internationally recognized for his research on lowdimensional structures and the physics and applications made possible by these structures. In recent years, his research has been directed toward the formation of ideal 1D heterostructured nanowires through self-assembly; inves tigation of their physical properties; and applications of semiconductor nanowires in electronics, photonics, and the life sciences.
He is a fellow of the Institute of Physics in the United Kingdom and a member of the Royal Swedish Academy of Sciences. He has authored more than 300 articles in refereed journals and has given approximately 150 plenary/invited talks at international conferences and workshops.
Samuelson can be reached at Solid State Physics,Lund University,Box 118, SE 221 00 Lund, Sweden; tel. 46-46-222-7679, fax 46-46-222-3637, and email@example.com