Institució Catalana de Recerca i Estudis Avançats (ICREA) Research Professor and Group Leader Jordi Arbiol and his team have recently moved to the ICN2. They have already signed a Nanoletters paper with their new affiliation where they have collaborated in the study, under different conditions, of the growth of nanowires and nanotubes of GaN using a technique called Selective Area Growth. Institut Català de Nanociència i Nanotecnologia (ICN2) is a growing institute consolidating his role as a leading nanoscience and nanotechnology focus in Southern Europe. One new step of this process is the incorporation of the ICREA Research Professor Jordi Arbiol and the Group of Advanced Electron Nanoscopy, now working under the affiliation of our Institute. The aim of the Group is developing and applying Electron Nanometrology tools, such as Transmission Electron Nanoscopy advanced techniques and related spectroscopies for Nanotechnology and Materials Science needs. They are able to observe optic properties of mater atom by atom and chemically analyse nanostructures at the atomic scale. Prof Arbiol and his team have already signed a contribution in a paper ("Position-Controlled Growth of GaN Nanowires and Nanotubes on Diamond by Molecular Beam Epitaxy") with their new affiliation. The article studies under different conditions the growth of nanowires and nanotubes of GaN using a technique called Selective Area Growth. The work was led from the Technische Universität München(Germany), with Prof Jose A. Garrido among its authors. The aim of this research is to find the optimum conditions for the growth of GaN nanowires. This means obtaining nanostructures with the best characteristics for developing applications. For instance, the position control of these structures on diamond is strongly desired for quantum computation.
A research to find the optimum conditions for the growth of GaN nanowires
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Nanopillar fabrication to lead to more efficient electronics
Seong Jin Koh Seong Jin Koh, an associate professor in the Materials Science & Engineering Department, has received a $300,000 National Science Foundation grant that could lead to a tenfold reduction in energy consumption of smart phones, laptops and tablets, which could result in an identical reduction in the frequency of battery charging for those devices.
"The key is that all transistor components reside in a single nanopillar and that electrons flow through it without being heated," said Koh, who added that a nanopillar is less than 50 nanometers in diameter. A human hair is about 100,000 nanometers thick. "This research will allow transistors to consume less energy and generate less heat. That greatly affects how well the transistors perform."
Khosrow Behbehani, dean of the College of Engineering, said other sectors besides individual electronic component users stand to benefit too.
Engineers now understand how complex carbon nanostructures form
Carbon nanotubes (CNTs) are microscopic tubular structures that engineers "grow" through a process conducted in a high-temperature furnace. The forces that create the CNT structures known as "forests" often are unpredictable and are mostly left to chance. Now, a University of Missouri researcher has developed a way to predict how these complicated structures are formed (, "Integrated simulation of active carbon nanotube forest growth and mechanical compression"). By understanding how CNT arrays are created, designers and engineers can better incorporate the highly adaptable material into devices and products such as baseball bats, aerospace wiring, combat body armor, computer logic components and micro sensors used in biomedical applications. 
On the left is a scanning electron micrograph of a carbon nanotube forest. The figure on the right is a numerically simulated CNT forest. (Image: Matt Maschmann) CNTs are much smaller than the width of a human hair and naturally form "forests" when they are created in large numbers (see photo). These forests, held together by a nanoscale adhesive force known as the van der Waals force, are categorized based on their rigidity or how they are aligned. For example, if CNTs are dense and well aligned, the material tends to be more rigid and can be useful for electrical and mechanical applications. If CNTs are disorganized, they tend to be softer and have entirely different sets of properties. "Scientists are still learning how carbon nanotube arrays form," said Matt Maschmann, assistant professor of mechanical and aerospace engineering in the College of Engineering at MU. "As they grow in relatively dense populations, mechanical forces combine them into vertically oriented assemblies known as forests or arrays. The complex structures they form help dictate the properties the CNT forests possess. We're working to identify the mechanisms behind how those forests form, how to control their formation and thus dictate future uses for CNTs." Currently, most models that examine CNT forests analyze what happens when you compress them or test their thermal or conductivity properties after they've formed. However, these models do not take into account the process by which that particular forest was created and struggle to capture realistic CNT forest structure. Experiments conducted in Maschmann's lab will help scientists understand the process and ultimately help control it, allowing engineers to create nanotube forests with desired mechanical, thermal and electrical properties. He uses modeling to map how nanotubes grow into particular types of forests before attempting to test their resulting properties. "The advantage of this approach is that we can map how different synthesis parameters, such as temperature and catalyst particle size, influence how nanotubes form while simultaneously testing the resulting CNT forests for how they will behave in one comprehensive simulation," Maschmann said. "I am very encouraged that the model successfully predicts how they are formed and their mechanical behaviors. Knowing how nanotubes are organized and behave will help engineers better integrate CNTs in practical, everyday applications."
On the left is a scanning electron micrograph of a carbon nanotube forest. The figure on the right is a numerically simulated CNT forest. (Image: Matt Maschmann) CNTs are much smaller than the width of a human hair and naturally form "forests" when they are created in large numbers (see photo). These forests, held together by a nanoscale adhesive force known as the van der Waals force, are categorized based on their rigidity or how they are aligned. For example, if CNTs are dense and well aligned, the material tends to be more rigid and can be useful for electrical and mechanical applications. If CNTs are disorganized, they tend to be softer and have entirely different sets of properties. "Scientists are still learning how carbon nanotube arrays form," said Matt Maschmann, assistant professor of mechanical and aerospace engineering in the College of Engineering at MU. "As they grow in relatively dense populations, mechanical forces combine them into vertically oriented assemblies known as forests or arrays. The complex structures they form help dictate the properties the CNT forests possess. We're working to identify the mechanisms behind how those forests form, how to control their formation and thus dictate future uses for CNTs." Currently, most models that examine CNT forests analyze what happens when you compress them or test their thermal or conductivity properties after they've formed. However, these models do not take into account the process by which that particular forest was created and struggle to capture realistic CNT forest structure. Experiments conducted in Maschmann's lab will help scientists understand the process and ultimately help control it, allowing engineers to create nanotube forests with desired mechanical, thermal and electrical properties. He uses modeling to map how nanotubes grow into particular types of forests before attempting to test their resulting properties. "The advantage of this approach is that we can map how different synthesis parameters, such as temperature and catalyst particle size, influence how nanotubes form while simultaneously testing the resulting CNT forests for how they will behave in one comprehensive simulation," Maschmann said. "I am very encouraged that the model successfully predicts how they are formed and their mechanical behaviors. Knowing how nanotubes are organized and behave will help engineers better integrate CNTs in practical, everyday applications."
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