Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Success in Self-Assembly of Quantum Dots with World’s Highest Density: Will Further Accelerate Research toward Realization of High Performance Quantum Dot Devices

Fig. :Atomic force microscope (AFM) image of ultra-high surface density quantum dots formed by reducing the amount of gallium irradiation to 3 monolayer at a growth temperature of 30°C. An ultra-high surface density of 7.3 x 1011/cm2 was achieved.
Fig. :Atomic force microscope (AFM) image of ultra-high surface density quantum dots formed by reducing the amount of gallium irradiation to 3 monolayer at a growth temperature of 30°C. An ultra-high surface density of 7.3 x 1011/cm2 was achieved.

Abstract:
The NIMS Photonic Materials Unit is developing an advanced self-assembly technique for semiconductor quantum dots called droplet epitaxy, which is an original NIMS technology, and recently succeeded in the development of a new self-assembly technique for quantum dots with the world's highest surface density, greatly exceeding the previously reported value.

Success in Self-Assembly of Quantum Dots with World’s Highest Density: Will Further Accelerate Research toward Realization of High Performance Quantum Dot Devices

Tsukuba, Japan | Posted on July 14th, 2012

Dr. Takaaki Mano, a Senior Researcher, Dr. Masafumi Jo, a Post Doctoral Fellow, and Dr. Yoshiki Sakuma, Group Leader of the Quantum Nanostructures Group, Photonic Materials Unit (Unit Director: Kazuaki Sakoda), National Institute for Materials Science (President: Sukekatsu Ushioda) are engaged in developing an advanced self-assembling technology for semiconductor quantum dots called droplet epitaxy, which is an original NIMS technology, and recently succeeded in the development of a new self-assembling technology for quantum dots with the world's highest surface density, greatly exceeding the previously reported value. In addition, the NIMS researchers observed strong photoluminescence (PL) emission from the assembled quantum dots groups, suggesting that the developed technology is also effective for realizing excellent crystal quality.

Quantum dots have attracted heightened attention in recent years as a technology for achieving substantial improvement in the properties of semiconductor lasers and development of ultra-high efficiency photovoltaic cells based on a new operating principle. In the newly-developed technology, (1) use of a substrate with a high index surface, (2) formation and crystallization of gallium droplets at near-room temperature, and (3) suppression of the droplet coalescence by optimization of the amount of supplied gallium were introduced in the gallium arsenide (GaAs) quantum dot formation by droplet epitaxy. As a result, the NIMS team succeeded in self-assembly of GaAs quantum dots with an extremely high surface density of 7.3 x 1011/cm2 in a lattice-matched system. The team also discovered that defects originating in crystallization at near-room temperature can be restored by applying ingenuity to the heat treatment process for the crystallized quantum dots, and strong PL emission can be observed from the quantum dots.

Droplet epitaxy has attracted attention as the only method which enables self-assembly of quantum dots in lattice-matched systems, and in principle has the advantage that a large number of high quality quantum dot layers can be stacked in close proximity with maintaining high crystallinity. Therefore, if the ultra-high density in-plane quantum dots developed in this research are stacked in close proximity, it will be possible to produce quantum dot materials with extremely high volumetric density, which cannot be realized with the conventional technology. Thus, it is expected to be possible to achieve higher performance in optical and electronic devices which use quantum dots as a result of this research achievement.

Details of this research were published in the online edition of Applied Physics Letters, which is an American scientific journal in the field of applied physics, and are scheduled for publication in Vol. 100, No. 21 of the print edition.

####

About National Institute for Materials Science

NIMS is Japan's sole Independent Administrative Institution (IAI) specializing in materials science. NIMS is charged with basic research and development of materials science, and to advance the level of expertise in the field.

For more information, please click here

Copyright © National Institute for Materials Science

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

A nanoscale wireless communication system via plasmonic antennas: Greater control affords 'in-plane' transmission of waves at or near visible light August 27th, 2016

Forces of nature: Interview with microscopy innovators Gerd Binnig and Christoph Gerber August 26th, 2016

A promising route to the scalable production of highly crystalline graphene films August 26th, 2016

Graphene under pressure August 26th, 2016

Self Assembly

Smarter self-assembly opens new pathways for nanotechnology: Brookhaven Lab scientists discover a way to create billionth-of-a-meter structures that snap together in complex patterns with unprecedented efficiency August 9th, 2016

Magnetic atoms arranged in neat rows: FAU physicists enable one-dimensional atom chains to grow August 5th, 2016

Accurate design of large icosahedral protein nanocages pushes bioengineering boundaries: Scientists used computational methods to build ten large, two-component, co-assembling icosahedral protein complexes the size of small virus coats July 25th, 2016

WSU researchers develop shape-changing 'smart' material: Heat, light stimulate self-assembly July 4th, 2016

Discoveries

A promising route to the scalable production of highly crystalline graphene films August 26th, 2016

Graphene under pressure August 26th, 2016

Nanofur for oil spill cleanup: Materials researchers learn from aquatic ferns: Hairy plant leaves are highly oil-absorbing / publication in bioinspiration & biomimetics / video on absorption capacity August 25th, 2016

Unraveling the crystal structure of a -70° Celsius superconductor, a world first: Significant advancement in the realization of room-temperature superconductors August 25th, 2016

Announcements

A nanoscale wireless communication system via plasmonic antennas: Greater control affords 'in-plane' transmission of waves at or near visible light August 27th, 2016

Forces of nature: Interview with microscopy innovators Gerd Binnig and Christoph Gerber August 26th, 2016

A promising route to the scalable production of highly crystalline graphene films August 26th, 2016

Graphene under pressure August 26th, 2016

Quantum Dots/Rods

Quantum dots with impermeable shell: A powerful tool for nanoengineering August 12th, 2016

Diamond-based light sources will lay a foundation for quantum communications of the future: Electrified quantum diamond can become the heart of quantum networks and computers of the future August 7th, 2016

A new type of quantum bits July 29th, 2016

Researchers develop faster, precise silica coating process for quantum dot nanorods July 12th, 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