Tag Archives: Lars Samuelson

LEDs (light-emitting diodes) that need less energy and give better light

A June 24, 2015 University of Copenhagen Niels Bohr Institute press release (also on EurekAlert), announces research that could lead to a brighter future (pun intended),

The researchers [from the Niels Bohr Institute] studied nanowires using X-ray microscopy and with this method they can pinpoint exactly how the nanowire should be designed to give the best properties. …

Nanowires are very small – about 2 micrometers high (1 micrometer is a thousandth of a millimetre) and 10-500 nanometers in diameter (1 nanometer is a thousandth of a micrometer). Nanowires for LEDs are made up of an inner core of gallium nitride (GaN) and a layer of indium-gallium-nitride (InGaN) on the outside, both of which are semiconducting materials.

“The light in such a diode is dependent on the mechanical strain that exists between the two materials and the strain is very dependent on how the two layers are in contact with each other. We have examined a number of nanowires using X-ray microscopy and even though the nanowires should in principle be identical, we can see that they are different and have very different structure,” explains Robert Feidenhans’l, professor and head of the Niels Bohr Institute at the University of Copenhagen.

Surprisingly efficient

The studies were performed using nanoscale X-ray microscopy in the electron synchrotron at DESY in Hamburg, Germany. The method is usually very time consuming and the results are often limited to very few or even a single study subject. But here researchers have managed to measure a series of upright nanowires all at once using a special design of a nanofocused X-ray without destroying the nanowires in the process.

“We measured 20 nanowires and when we saw the images, we were very surprised because you could clearly see the details of each nanowire. You can see the structure of both the inner core and the outer layer. If there are defects in the structure or if they are slightly bent, they do not function as well. So we can identify exactly which nanowires are the best and have the most efficient core/shell structure,” explains Tomas Stankevic, a PhD student in the research group ‘Neutron and X-ray Scattering’ at the Niels Bohr Institute at the University of Copenhagen.

The nanowires are produced by a company in Sweden and this new information can be used to tweak the layer structure in the nanowires. Professor Robert Feidenhans’l explains that there is great potential in such nanowires. They will provide a more natural light in LEDs and they will use much less power. In addition, they could be used in smart phones, televisions and many forms of lighting.

The researchers expect that things could go very quickly and that they may already be in use within five years.

Here’s a link to and a citation for the paper,

Fast Strain Mapping of Nanowire Light-Emitting Diodes Using Nanofocused X-ray Beams by Tomaš Stankevič, Emelie Hilner, Frank Seiboth, Rafal Ciechonski, Giuliano Vescovi, Olga Kryliouk, Ulf Johansson, Lars Samuelson, Gerd Wellenreuther, Gerald Falkenberg, Robert Feidenhans’l, and Anders Mikkelsen.
ACS Nano, Article ASAP DOI: 10.1021/acsnano.5b01291
Publication Date (Web): June 19, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

Swedish nano plans in Lund

It was a bit a surprise to learn a few years ago that Chalmers University of Technology (Sweden) was the lead in the European Union’s Graphene Flagship project. I was expecting the lead to be one of the British universities, specifically, the University of Manchester seeing that graphene was first isolated there by Nobel Laureates Andre Geim and Konstantan (Kostya) Novoselov, Since then, I’ve kept an eye on the Swedish nanotechnology enterprise and am pleased to have received a Feb. 13, 2014 announcement about hopes for establishing a new nano centre in Lund, Sweden,

A production facility for start-ups in the field of nanotechnology may be built in the Science Village in Lund, a world-class research and innovation village that is also home to ESS, the European Spallation Source.

“With this new facility, we want to create the conditions to enable new companies to develop from the R&D phase to full production, without needing to leave Sweden,” says Lars Samuelson, Professor of Nanophysics at Lund University.

The project originates from the successful research into nanowires at Lund University, which has resulted in nanotechnology companies like Glo AB and Sol Voltaics AB. Glo was forced to move to Silicon Valley, however, to launch large-scale mass production.

The infrastructure would be intended for companies and researchers in the whole of Sweden who want to develop products with industry standards without needing to invest in expensive equipment themselves.

Samuelson sees more business opportunities for nanowires. In addition to Glo’s light-emitting diodes and Sol Voltaics’ solar cells, Lars Samuelson believes there is potential for new companies focused on applications within electronics, UV light-emitting diodes and biomedicine.

Alongside this project, Lund University is working to extend the Lund Nano Lab which is a pure research laboratory for research on nanowires. This is run by Lund University, whereas the industrial facility is a project outside the University. Together, these two initiatives constitute a way of generating the whole value chain from research to market.

The preliminary study into the facility, funded by Vinnova [Sweden’s innovation agency] and Region Skåne and initiated by the Nanometer Structure Consortium at Lund University, is to result in an estimate of investment requirements and market potential, as well as a proposal for a business model. The aim is to become internationally competitive and financially self-sufficient.

A cluster of companies and services, close to the University’s research, is expected to develop around the common equipment for nanoproduction.

About the Nanometer Structure Consortium at Lund University nmC@LU

The Nanometer Structure Consortium at Lund University was founded in 1989. Today, it is one of Sweden’s Strategic Research Areas, engaging more than 250 researchers at the Faculties of Engineering, Science and Medicine. The research focuses on the materials science of nanostructures and its applications within fundamental science, electronics, optoelectronics, energy conversion and life sciences. Former start-ups from the Nanometer Structure Consortium currently employ around 150 people and have attracted private investments of over one billion Swedish crowns.

I suspect this announcement is intended to both raise awareness and, more importantly, attract potential investors as it goes on to provide a number of contacts,

Initiator: Lars Samuelson, Professor, Nanometer Structure Consortium, Lund University, tel. +46 46 222 76 79, lars.samuelson@ftf.lth.se

Chair of the project’s steering group: Heiner Linke, Professor, Coordinator of the Nanometer Structure Consortium, Lund University, tel. +46 46 222 42 45, heiner.linke@ftf.lth.se

Project manager: Yvonne Mårtensson, Nanova, tel. +46 708 337782, yvonne.martensson@nanova.se

Daniel Kronmann, Innovation Systems Unit, Region Skåne, 040-675 34 36, 0706-15 28 10, Daniel.Kronmann@skane.se

International Media Officer
+46 72 7074546

I wish them good luck with their plans.

US Air Force wants to merge classical and quantum physics

The US Air Force wants to merge classical and quantum physics for practical purposes according to a May 5, 2014 news item on Azonano,

The Air Force Office of Scientific Research has selected the Harvard School of Engineering and Applied Sciences (SEAS) to lead a multidisciplinary effort that will merge research in classical and quantum physics and accelerate the development of advanced optical technologies.

Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering, will lead this Multidisciplinary University Research Initiative [MURI] with a world-class team of collaborators from Harvard, Columbia University, Purdue University, Stanford University, the University of Pennsylvania, Lund University, and the University of Southampton.

The grant is expected to advance physics and materials science in directions that could lead to very sophisticated lenses, communication technologies, quantum information devices, and imaging technologies.

“This is one of the world’s strongest possible teams,” said Capasso. “I am proud to lead this group of people, who are internationally renowned experts in their fields, and I believe we can really break new ground.”

A May 1, 2014 Harvard University School of Engineering and Applied Sciences news release, which originated the news item, provides a description of project focus: nanophotonics and metamaterials along with some details of Capasso’s work in these areas (Note: Links have been removed),

The premise of nanophotonics is that light can interact with matter in unusual ways when the material incorporates tiny metallic or dielectric features that are separated by a distance shorter than the wavelength of the light. Metamaterials are engineered materials that exploit these phenomena, producing strange effects, enabling light to bend unnaturally, twist into a vortex, or disappear entirely. Yet the fabrication of thick, or bulk, metamaterials—that manipulate light as it passes through the material—has proven very challenging.

Recent research by Capasso and others in the field has demonstrated that with the right device structure, the critical manipulations can actually be confined to the very surface of the material—what they have dubbed a “metasurface.” These metasurfaces can impart an instantaneous shift in the phase, amplitude, and polarization of light, effectively controlling optical properties on demand. Importantly, they can be created in the lab using fairly common fabrication techniques.

At Harvard, the research has produced devices like an extremely thin, flat lens, and a material that absorbs 99.75% of infrared light. But, so far, such devices have been built to order—brilliantly suited to a single task, but not tunable.

This project, however,is focused on the future (Note: Links have been removed),

“Can we make a rapidly configurable metasurface so that we can change it in real time and quickly? That’s really a visionary frontier,” said Capasso. “We want to go all the way from the fundamental physics to the material building blocks and then the actual devices, to arrive at some sort of system demonstration.”

The proposed research also goes further. A key thrust of the project involves combining nanophotonics with research in quantum photonics. By exploiting the quantum effects of luminescent atomic impurities in diamond, for example, physicists and engineers have shown that light can be captured, stored, manipulated, and emitted as a controlled stream of single photons. These types of devices are essential building blocks for the realization of secure quantum communication systems and quantum computers. By coupling these quantum systems with metasurfaces—creating so-called quantum metasurfaces—the team believes it is possible to achieve an unprecedented level of control over the emission of photons.

“Just 20 years ago, the notion that photons could be manipulated at the subwavelength scale was thought to be some exotic thing, far fetched and of very limited use,” said Capasso. “But basic research opens up new avenues. In hindsight we know that new discoveries tend to lead to other technology developments in unexpected ways.”

The research team includes experts in theoretical physics, metamaterials, nanophotonic circuitry, quantum devices, plasmonics, nanofabrication, and computational modeling. Co-principal investigator Marko Lončar is the Tiantsai Lin Professor of Electrical Engineering at Harvard SEAS. Co-PI Nanfang Yu, Ph.D. ’09, developed expertise in metasurfaces as a student in Capasso’s Harvard laboratory; he is now an assistant professor of applied physics at Columbia. Additional co-PIs include Alexandra Boltasseva and Vladimir Shalaev at Purdue, Mark Brongersma at Stanford, and Nader Engheta at the University of Pennsylvania. Lars Samuelson (Lund University) and Nikolay Zheludev (University of Southampton) will also participate.

The bulk of the funding will support talented graduate students at the lead institutions.

The project, titled “Active Metasurfaces for Advanced Wavefront Engineering and Waveguiding,” is among 24 planned MURI awards selected from 361 white papers and 88 detailed proposals evaluated by a panel of experts; each award is subject to successful negotiation. The anticipated amount of the Harvard-led grant is up to $6.5 million for three to five years.

For anyone who’s not familiar (that includes me, anyway) with MURI awards, there’s this from Wikipedia (Note: links have been removed),

Multidisciplinary University Research Initiative (MURI) is a basic research program sponsored by the US Department of Defense (DoD). Currently each MURI award is about $1.5 million a year for five years.

I gather that in addition to the Air Force, the Army and the Navy also award MURI funds.