Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Electrons and Lattice Vibrations—A Strong Team in the Nano World

Measured two-dimensional spectrum. Without the interaction of the electron with lattice vibrations there would be no signal in the range shown.
Measured two-dimensional spectrum. Without the interaction of the electron with lattice vibrations there would be no signal in the range shown.

Abstract:
Using a newly developed type of spectroscopy, Berlin researchers have shown that electrons in a semiconductor are best described as a cloud with a size of a few nanometer (one nanometer is one billionth of one meter). The cloud size is determined by the interaction of the electron with vibrations in the crystal lattice.

Electrons and Lattice Vibrations—A Strong Team in the Nano World

Berlin, Germany | Posted on August 6th, 2011

Semiconductor electronics generates, controls, and amplifies electrical current in devices like the transistor. The carriers of the electric current are mobile electrons, which move with high velocities through the crystal lattice of the semiconductor. Doing this, they lose part of their kinetic energy by causing atoms in the lattice to vibrate. In semiconductors like gallium arsenide the positively and negatively charged ions of the crystal lattice vibrate with an extremely short period of 100 fs (1 fs = 10-15 s = 1 billionth part of one millionth of a second). In the microcosm of electrons and ions such vibrations are quantized. This means that the vibrational energy can only be an integer multiple of a vibrational quantum, also known as a phonon. When an electron interacts with the crystal lattice (the so called electron-phonon interaction), energy is transferred from the electron to the lattice in the form of such vibrational quanta.

Berlin researchers report in the latest issue of the scientific journal Physical Review Letters that the strength of the electron-phonon interaction depends sensitively on the electron size, i.e., on the spatial extent of its charge cloud. Experiments in the time range of the lattice vibration show that reducing the electron size leads to an increase of the interaction by up to a factor of 50. This results in a strong coupling of the movements of electrons and ions. Electron and phonon together form a new quasi particle, a polaron.

To visualize this phenomenon, the researchers used a nanostructure made from gallium arsenide and gallium aluminum arsenide, in which the energies of the movements of electrons and ions were tuned to each other. The coupling of both movements was shown by a new optical technique. Several ultrashort light pulses in the infrared excite the system under study. The subsequent emission of light by the moving charge carriers is measured in real time. In this way two-dimensional nonlinear spectra (see Fig.) are generated, which allow the detailed investigation of coupled transitions and the determination of the electron-phonon coupling strength. From the coupling strength one finds the size of the electron cloud, which is just 3-4 nanometers (1 nanometer = 10-9 m = 1 billionth of one meter). Furthermore, this new method shows for the first time the importance of electron-phonon coupling for optical spectra of semiconductors. This is of interest for the development of optoelectronic devices with custom-tailored optical and electric properties

Full bibliographic informationW. Kuehn et al., Phys. Rev. Lett. 107, 067401 (2011); J. Phys. Chem. B 115, 5448 (2011).

####

For more information, please click here

Contacts:
Christine Vollgraf
+49-30-63923337


Klaus Reimann
Michael Woerner
Thomas Elsaesser
Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie
Tel.: +49 30 6392 1470

Copyright © AlphaGalileo

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Ultrathin, flat lens resolves chirality and color: Multifunctional lens could replace bulky, expensive machines June 25th, 2016

Nanotechnology and math deliver two-in-one punch for cancer therapy resistance June 24th, 2016

Researchers discover new chemical sensing technique: Technique allows sharper detail -- and more information -- with near infrared light June 24th, 2016

Soft decoupling of organic molecules on metal June 23rd, 2016

Chip Technology

GraphExeter illuminates bright new future for flexible lighting devices June 23rd, 2016

Soft decoupling of organic molecules on metal June 23rd, 2016

Particle zoo in a quantum computer: First experimental quantum simulation of particle physics phenomena June 23rd, 2016

Nanometrics to Participate in the 8th Annual CEO Investor Summit: Investor Event Held Concurrently with SEMICON West 2016 in San Francisco June 22nd, 2016

Discoveries

Ultrathin, flat lens resolves chirality and color: Multifunctional lens could replace bulky, expensive machines June 25th, 2016

Nanotechnology and math deliver two-in-one punch for cancer therapy resistance June 24th, 2016

Researchers discover new chemical sensing technique: Technique allows sharper detail -- and more information -- with near infrared light June 24th, 2016

Soft decoupling of organic molecules on metal June 23rd, 2016

Announcements

Ultrathin, flat lens resolves chirality and color: Multifunctional lens could replace bulky, expensive machines June 25th, 2016

Nanotechnology and math deliver two-in-one punch for cancer therapy resistance June 24th, 2016

Researchers discover new chemical sensing technique: Technique allows sharper detail -- and more information -- with near infrared light June 24th, 2016

Soft decoupling of organic molecules on metal June 23rd, 2016

Photonics/Optics/Lasers

Marrying superconductors, lasers, and Bose-Einstein condensates: Chapman University Institute for Quantum Studies (IQS) member Yutaka Shikano, Ph.D., recently had research published in Scientific Reports June 20th, 2016

A new trick for controlling emission direction in microlasers June 20th, 2016

A new form of hybrid photodetectors with quantum dots and graphene June 19th, 2016

New approach to microlasers: Technique for 'phase locking' arrays of tiny lasers could lead to terahertz security scanners June 17th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic