Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Etched Quantum Dots Shape Up as Single Photon Emitters, NIST Tests Show

Colorized micrograph of quantum dots made using electron beam lithography and etching. This type of quantum dot can be shaped and positioned more reliably than dots made with conventional crystal growth methods.
Credit: Verma/NIST
Colorized micrograph of quantum dots made using electron beam lithography and etching. This type of quantum dot can be shaped and positioned more reliably than dots made with conventional crystal growth methods.

Credit: Verma/NIST

Abstract:
Like snowflakes or fingerprints, no two quantum dots are identical. But a new etching method for shaping and positioning these semiconductor nanocrystals might change that. What's more, tests at the National Institute of Standards and Technology (NIST) confirm that etched quantum dots emit single particles of light (photons), boosting prospects for powering new types of devices for quantum communications.

Etched Quantum Dots Shape Up as Single Photon Emitters, NIST Tests Show

Gaithersburg, MD | Posted on February 26th, 2011

The conventional way to build quantum dots—at NIST and elsewhere—is to grow them like crystals in a solution, but this somewhat haphazard process results in irregular shapes. The new, more precise process was developed by NIST postdoctoral researcher Varun Verma when he was a student at the University of Illinois. Verma uses electron beam lithography and etching to carve quantum dots inside a semiconductor sandwich (called a quantum well) that confines particles in two dimensions. Lithography controls the dot's size and position, while sandwich thickness and composition—as well as dot size—can be used to tune the color of the dot's light emissions.

Some quantum dots are capable of emitting individual, isolated photons on demand, a crucial trait for quantum information systems that encode information by manipulating single photons. In new work reported in Optics Express,* NIST tests demonstrated that the lithographed and etched quantum dots do indeed work as sources of single photons. The tests were performed on dots made of indium gallium arsenide. Dots of various diameters were patterned in specific positions in square arrays. Using a laser to excite individual dots and a photon detector to analyze emissions, NIST researchers found that dots 35 nanometers (nm) wide, for instance, emitted nearly all light at a wavelength of 888.6 nm. The timing pattern indicated that the light was emitted as a train of single photons.

NIST researchers now plan to construct reflective cavities around individual etched dots to guide their light emissions. If each dot can emit most photons perpendicular to the chip surface, more light can be collected to make a more efficient single photon source. Vertical emission has been demonstrated with crystal-grown quantum dots, but these dots can't be positioned or distributed reliably in cavities. Etched dots offer not only precise positioning but also the possibility of making identical dots, which could be used to generate special states of light such as two or more photons that are entangled, a quantum phenomenon that links their properties even at a distance.

The quantum dots tested in the experiments were made at NIST. A final step was carried out at the University of Illinois, where a crystal layer was grown over the dots to form clean interfaces.

* V.B. Verma, M.J. Stevens, K.L. Silverman, N.L. Dias, A. Garg, J.J. Coleman and R.P. Mirin. Photon antibunching from a single lithographically defined InGaAs/GaAs quantum dot. Optics Express. Vol. 19, No. 5, Feb. 28, 2011, p. 4182. Posted online Feb. 17, 2011.

####

About NIST
The National Institute of Standards and Technology (NIST) is an agency of the U.S. Commerce Department.

For more information, please click here

Contacts:
Laura Ost
303-497-4880

Copyright © NIST

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

U.S. Air Force Research Lab Taps IBM to Build Brain-Inspired AI Supercomputing System: Equal to 64 million neurons, new neurosynaptic supercomputing system will power complex AI tasks at unprecedented speed and energy efficiency June 23rd, 2017

Rice U. chemists create 3-D printed graphene foam June 22nd, 2017

Tiny bubbles provide tremendous propulsion in new microparticles research-Ben-Gurion U. June 21st, 2017

Enhanced photocatalytic activity by Cu2O nanoparticles integrated H2Ti3O7 nanotubes June 21st, 2017

Quantum Computing

Microsoft, Purdue collaborate to advance quantum computing May 30th, 2017

Looking for the quantum frontier: Beyond classical computing without fault-tolerance? April 27th, 2017

Harris & Harris Group Issues Its Financial Statements as of December 31, 2016, Posts Its Annual Shareholder Letter, And Will Host a Conference Call for Shareholders on Friday, March 17, 2017 March 15th, 2017

Sorting machine for atoms:Researchers at the University of Bonn clear a further hurdle on the path to creating quantum computers February 10th, 2017

Discoveries

Rice U. chemists create 3-D printed graphene foam June 22nd, 2017

Tiny bubbles provide tremendous propulsion in new microparticles research-Ben-Gurion U. June 21st, 2017

Enhanced photocatalytic activity by Cu2O nanoparticles integrated H2Ti3O7 nanotubes June 21st, 2017

Researchers developed nanoparticle based contrast agent for dual modal imaging of cancer June 21st, 2017

Announcements

U.S. Air Force Research Lab Taps IBM to Build Brain-Inspired AI Supercomputing System: Equal to 64 million neurons, new neurosynaptic supercomputing system will power complex AI tasks at unprecedented speed and energy efficiency June 23rd, 2017

Rice U. chemists create 3-D printed graphene foam June 22nd, 2017

Tiny bubbles provide tremendous propulsion in new microparticles research-Ben-Gurion U. June 21st, 2017

Enhanced photocatalytic activity by Cu2O nanoparticles integrated H2Ti3O7 nanotubes June 21st, 2017

Quantum Dots/Rods

Graphene and quantum dots put in motion a CMOS-integrated camera that can see the invisible May 29th, 2017

The brighter side of twisted polymers: Conjugated polymers designed with a twist produce tiny, brightly fluorescent particles with broad applications May 16th, 2017

Nanoparticles open new window for biological imaging: “Quantum dots” that emit infrared light enable highly detailed images of internal body structures April 10th, 2017

Particle Works creates range of high performance quantum dots February 23rd, 2017

Quantum nanoscience

Oxford Instruments congratulates Lancaster University for inaugurating the IsoLab, built for studying quantum systems June 20th, 2017

In atomic propellers, quantum phenomena can mimic everyday physics June 1st, 2017

Unveiling the quantum necklace: Researchers simulate quantum necklace-like structures in superfluids May 26th, 2017

The speed limit for intra-chip communications in microprocessors of the future January 23rd, 2017

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