Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

NIST method may help optimize light-emitting semiconductors

20.02.2006


Physicists at JILA have demonstrated an ultrafast laser technique for "seeing" once-hidden electronic behavior in semiconductors, which eventually could be useful in more predictable design of optoelectronic devices, including semiconductor lasers and white light-emitting diodes.


What do you see in these Rorschach-blot-like images? JILA physicists see the once-hidden electronic behavior of semiconductors. The computer plots show how energy intensity (ranging from low in blue to high in red) varies as electronic structures called excitons absorblaser light and emit energy at various frequencies. The pair of similar "butterflies" indicates that an exciton is absorbing and emitting energy in a predictable pattern. Credit: JILA



The work at JILA, a joint institute of the National Institute of Standards and Technology and the University of Colorado at Boulder, is described in the Feb. 10 issue of Physical Review Letters.

The technique manipulates light energy and wave patterns to reveal subtle behavior, such as correlated oscillations of two objects. Such correlations are important because they may allow researchers to more accurately predict the emission frequencies produced by an optoelectronic device based on its structure and semiconductor materials.


The method was developed originally by other researchers years ago for probing couplings between spinning nuclei as an indicator of molecular structure, and it led to a Nobel prize; more recently, scientists have been trying to use it to study vibrations in chemical bonds. The JILA team is the first to show the approach offers new insights into electronic properties of semiconductors. The use of light as a precision tool to manage electronic behavior could lead to improved optoelectronic devices.

In the JILA technique, a sample made of thin layers of gallium arsenide is hit with a continuous series of three near-infrared laser pulses lasting just 100 femtoseconds each. Trillions of electronic structures called excitons are formed. They consist of "excited" electrons and the "holes" they leave behind as they jump to higher energy vibration patterns. By changing the timing of the laser pulses and analyzing the wave patterns of the light and exciton oscillations, the JILA scientists figured out how to produce and identify correlations between absorption and emission of light from the material. The presence or absence of correlations can be seen in a computer plot of the frequency and wave pattern of the absorbed and emitted light. Correlations are revealed as a pair of similar butterfly-shaped plots.

Laura Ost | EurekAlert!
Further information:
http://www.nist.gov

More articles from Physics and Astronomy:

nachricht Hope to discover sure signs of life on Mars? New research says look for the element vanadium
22.09.2017 | University of Kansas

nachricht Calculating quietness
22.09.2017 | Forschungszentrum MATHEON ECMath

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

Hope to discover sure signs of life on Mars? New research says look for the element vanadium

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>