Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Clear Picture Of 'Birth' Of Semiconductor Nanostructures

Abstract:
Information will help researchers better understand and use materials that could lead to small, efficient and powerful computers, communication devices and scientific instruments.

Researchers Develop Clear Picture Of 'Birth' Of Semiconductor Nanostructures

Fayetteville, AR | April 04, 2005

University of Arkansas researchers have witnessed the birth of a quantum dot and learned more about how such atomic islands form and grow, using the ultrahigh vacuum facility on campus. This information will help researchers better understand and use materials that could lead to small, efficient and powerful computers, communication devices and scientific instruments.

Seongho Cho, Zhiming Wang, and Gregory Salamo report their findings in the upcoming issue of the journal Applied Physics Letters.

"We have changed the way people have to think about how nanostructures grow on a surface," said Salamo, University Professor of physics. "People had a different idea of how these islands formed, but until now there was not direct evidence."

The researchers combined the molecular-beam epitaxy machine, which creates material atom by atom, with scanning tunneling microscopy, which can observe the atoms, to witness the creation of quantum dots, or atomic islands, of indium gallium arsenide (InGaAs) atoms atop a gallium arsenide (GaAs) surface. InGaAs is a material of electronic and optical interest for properties that could enhance communications equipment, computers and electronics.

At the atomic level, a surface is characterized by small monolayer "steps." Until now, researchers believed that the first atom of a quantum dot would land at the base of the step, rather than further out towards the edge of the step. The work of Cho, Wang and Salamo shows instead that the first atom lands at the step's edge.

"An island growing from below the step edge must first build up to a height equal to the step. This is unnecessary since it could more easily just start from the top of the step," said Wang, a research professor working with Salamo.

The researchers found that the first atoms of InGaAs land side by side atop the GaAs surface and experience a strain, much like a person trying to squeeze into an already crowded line. Therefore, after a short time, it becomes easier for an InGaAs atom to land atop other InGaAs atoms instead of on the initial surface. Also, fewer atoms land on a layer as the layers build up, allowing the atoms to have more space and experience less strain. The researchers witnessed this sequential, upward, narrowing growth as they studied the formation of the InGaAs quantum dots, which ended by forming a pyramid-like structure.

This observation also is significant because it may offer a more general explanation of how other semiconductor materials behave at the nanoscale, Wang said.

"It was predicted by previous theory independent of materials, but wasn't observed for InGaAs islands before," he said.

"We do not yet have a complete picture of how these quantum dots grow," Salamo said. "But we have added to the picture."

This picture has implications that extend beyond semiconductors, he added.

"How these small structures grow and how they behave tells us about the rules that govern small structures in general," Salamo said. "Cells are small. DNA is small. Everything is composed of small structures. When you understand how things go together, they supply a library for looking at other things in science."

####



Contact:
Zhiming M. Wang
Research professor of microelectronics-photonics
(479) 575-4217
zmwang@uark.edu

Gregory J. Salamo
University Professor of physics
Fulbright College
(479) 575-5931
salamo@uark.edu

Melissa Lutz Blouin
Science and research communications manager
(479) 575-5555
blouin@uark.edu

Copyright © University of Arkansas

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

Possible Futures

Imaging electric charge propagating along microbial nanowires October 20th, 2014

Superconducting circuits, simplified: New circuit design could unlock the power of experimental superconducting computer chips October 18th, 2014

Nanocoatings Market By Product Is Expected To Reach USD 8.17 Billion By 2020: Grand View Research, Inc. October 15th, 2014

Perpetuus Carbon Group Receives Independent Verification of its Production Capacity for Graphenes at 140 Tonnes per Annum: Perpetuus Becomes the First Manufacturer in the Sector to Allow Third Party Audit October 7th, 2014

Nanoelectronics

Crystallizing the DNA nanotechnology dream: Scientists have designed the first large DNA crystals with precisely prescribed depths and complex 3D features, which could create revolutionary nanodevices October 20th, 2014

Imaging electric charge propagating along microbial nanowires October 20th, 2014

Future computers could be built from magnetic 'tornadoes' October 14th, 2014

Aledia’s Nanowire LED Technology Endorsed By 2014 Physics Nobel Prize Winner: Hiroshi Amano Serves on Company’s Scientific Advisory Board October 13th, 2014

Discoveries

Nitrogen Doped Graphene Characterized by Iranian, Russian, German Scientists October 21st, 2014

Design of micro and nanoparticles to improve treatments for Alzheimers and Parkinsons: At the Faculty of Pharmacy of the UPV/EHU-University of the Basque Country encapsulation techniques are being developed to deliver correctly and effectively certain drugs October 20th, 2014

Physicists build reversible laser tractor beam October 20th, 2014

Removal of Limitations of Composites at Superheat Temperatures October 20th, 2014

Materials/Metamaterials

Removal of Limitations of Composites at Superheat Temperatures October 20th, 2014

Nanotechnology Improves Quality of Anti-Corrosive Coatings October 17th, 2014

Graphenea opens US branch October 16th, 2014

3DXNano™ ESD Carbon Nanotube 3D Printing Filament - optimized for demanding 3D printing applications in the semi-con and electronics industry October 16th, 2014

Announcements

Nitrogen Doped Graphene Characterized by Iranian, Russian, German Scientists October 21st, 2014

Design of micro and nanoparticles to improve treatments for Alzheimers and Parkinsons: At the Faculty of Pharmacy of the UPV/EHU-University of the Basque Country encapsulation techniques are being developed to deliver correctly and effectively certain drugs October 20th, 2014

Physicists build reversible laser tractor beam October 20th, 2014

Removal of Limitations of Composites at Superheat Temperatures October 20th, 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