Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

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

Scientists reveal breakthrough in optical fiber communications December 21st, 2014

Atom-thick CCD could capture images: Rice University scientists develop two-dimensional, light-sensitive material December 20th, 2014

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Instant-start computers possible with new breakthrough December 19th, 2014

Self Assembly

Revealed: How bacteria drill into our cells and kill them December 2nd, 2014

Live Images from the Nano-cosmos: Researchers watch layers of football molecules grow 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

NYU Researchers Break Nano Barrier to Engineer the First Protein Microfiber October 23rd, 2014

Discoveries

Scientists reveal breakthrough in optical fiber communications December 21st, 2014

Atom-thick CCD could capture images: Rice University scientists develop two-dimensional, light-sensitive material December 20th, 2014

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Instant-start computers possible with new breakthrough December 19th, 2014

Announcements

Scientists reveal breakthrough in optical fiber communications December 21st, 2014

Atom-thick CCD could capture images: Rice University scientists develop two-dimensional, light-sensitive material December 20th, 2014

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Instant-start computers possible with new breakthrough December 19th, 2014

Quantum Dots/Rods

Oregon researchers glimpse pathway of sunlight to electricity: Collaboration with Lund University uses modified UO spectroscopy equipment to study 'maze' of connections in photoactive quantum dots December 19th, 2014

Scientists trace nanoparticles from plants to caterpillars: Rice University study examines how nanoparticles behave in food chain December 16th, 2014

TCL Launches World’s Most Advanced TV in the World’s Largest Market: New Quantum Dot TVs with Color IQ™ Optics Deliver OLED-Quality Color at a Fraction of the Price December 15th, 2014

Electron pairs on demand: Controlled emission and spatial splitting of electron pairs demonstrated December 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