Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

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

NMTI announces breakthrough solutions for HAMR nanoantenna for next-generation ultra-high density magnetic storage November 21st, 2014

Leica Microsystems Presents Universal Hybrid Detector for Single Molecule Detection and Imaging at SfN and ASCB: Leica HyD SMD - the Optimal Detector for Precise and Reliable SMD data November 20th, 2014

Silver Nanoparticles Produced in Iran from Forest Plants Extract November 20th, 2014

Nano Sorbents Able to Remove Pollutions Caused by Oil Derivatives November 20th, 2014

Chip Technology

Nanometrics Announces Upcoming Investor Events November 19th, 2014

A novel method for identifying the body’s ‘noisiest’ networks November 19th, 2014

Researchers create & control spin waves, lifting prospects for enhanced info processing November 17th, 2014

VDMA Electronics Production Equipment: Growth track for 2014 and 2015 confirmed: Business climate survey shows robust industry sector November 14th, 2014

Discoveries

NMTI announces breakthrough solutions for HAMR nanoantenna for next-generation ultra-high density magnetic storage November 21st, 2014

UO-industry collaboration points to improved nanomaterials: University of Oregon microscope puts spotlight on the surface structure of quantum dots for designing new solar devices November 20th, 2014

Silver Nanoparticles Produced in Iran from Forest Plants Extract November 20th, 2014

Nano Sorbents Able to Remove Pollutions Caused by Oil Derivatives November 20th, 2014

Announcements

NMTI announces breakthrough solutions for HAMR nanoantenna for next-generation ultra-high density magnetic storage November 21st, 2014

Leica Microsystems Presents Universal Hybrid Detector for Single Molecule Detection and Imaging at SfN and ASCB: Leica HyD SMD - the Optimal Detector for Precise and Reliable SMD data November 20th, 2014

Silver Nanoparticles Produced in Iran from Forest Plants Extract November 20th, 2014

Nano Sorbents Able to Remove Pollutions Caused by Oil Derivatives November 20th, 2014

Photonics/Optics/Lasers

NRL Scientists Discover Novel Metamaterial Properties within Hexagonal Boron Nitride November 20th, 2014

Penn engineers efficiently 'mix' light at the nanoscale November 17th, 2014

'Direct writing' of diamond patterns from graphite a potential technological leap November 5th, 2014

Outsmarting Thermodynamics in Self-assembly of Nanostructures: Berkeley Lab reports method for symmetry-breaking in feedback-driven self-assembly of optical metamaterials November 4th, 2014

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







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE