Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Discovery of 'Doping' Mechanism in Semiconductor Nanocrystals

Abstract:
Novel electronic devices based upon nanotechnology may soon be realized due to a new understanding of how impurities, or 'dopants,' can be intentionally incorporated into semiconductor nanocrystals.

Discovery of 'Doping' Mechanism in Semiconductor Nanocrystals Advances Potential of Nanotechnology

July 07, 2005

This understanding, announced today by researchers at the Naval Research Laboratory and the University of Minnesota (UMN), should help enable a variety of new technologies ranging from high-efficiency solar-cells and lasers to futuristic 'spintronic' and ultra-sensitive biodetection devices. The complete findings of the study are published in the July 7, 2005, issue of the journal Nature.

Nanocrystals are tiny semiconductor particles just a few millionths of a millimeter across. Due to their small size, they exhibit unique electronic, optical, and magnetic properties that can be utilized in a variety of technologies. To move toward this end, chemical methods have been optimized over the last 20 years to synthesize extremely pure nanocrystals. More problematic, however, has been the goal of controllably incorporating selected impurities into these particles. Conventional semiconductor devices, such as the transistor, would not operate without such impurities. Moreover, theory predicts that dopants should have even greater impact on semiconductor nanocrystals. Thus, doping is a critical step for tailoring their properties for specific applications.

A long-standing mystery has been why impurities could not be incorporated into some types of semiconductor nanocrystals. The findings by NRL and UMN researchers establish the underlying reasons for these difficulties, and provide a rational foundation for resolving them in a wide variety of nanocrystal systems. "The key lies in the nanocrystal's surface," said Dr. Steven Erwin, a physicist at NRL and lead theorist on the project. "If an impurity atom can stick, or 'adsorb,' to the surface strongly enough, it can eventually be incorporated into the nanocrystal as it grows. If the impurity binds to the nanocrystal surface too weakly, or if the strongly binding surfaces are only a small fraction of the total, then doping will be difficult." From calculations based on this central idea, the team could predict conditions favorable for doping. Experiments at UMN then confirmed these predictions, including the incorporation of impurities into nanocrystals that were previously believed to be undopable. Thus, a variety of new doped nanocrystals may now be possible, an important advance toward future nanotechnologies.

According to Dr. David Norris, an Associate Professor of Chemical Engineering and Materials Science at UMN and the lead experimentalist on the team, "an exciting aspect of these results is that they overturn a common belief that nanocrystals are intrinsically difficult to dope because they somehow 'self-purify' by expelling impurities from their interior. According to this view, the same mechanisms that made it possible to grow very pure nanocrystals also made it extremely difficult to dope them. We have shown that doping difficulties are not intrinsic, and indeed are amenable to systematic optimization using straightforward methods from physical chemistry."

Future efforts will focus on incorporating impurities which are chosen for specific applications. For example, solar cells and lasers could benefit from impurities that add an additional electrical charge to the nanocrystal. In addition, impurities will be chosen to explore the use of nanocrystals in spin electronics (or "spintronics"). Spintronic devices utilize the fact that electrons not only possess charge, but also a quantum mechanical spin. The spin provides an additional degree of freedom that can be exploited in devices to realize a host of new spintronic technologies, from. nonvolatile "instant-on" computers to so-called "reconfigurable logic" elements whose underlying circuitry can be changed on-the-fly.

The research was conducted by Dr. Steven Erwin, Dr. Michael Haftel, and Dr. Alexander Efros from NRL's Materials Science and Technology Division; Dr. Thomas Kennedy from NRL's Electronics Science and Technology Division; and Ms. Lijun Zu and Professor David Norris from the Department of Chemical Engineering and Materials Science at the University of Minnesota. The Office of Naval Research and the National Science Foundation provided funding for the research.


####

About NRL:
NRL conducts a broadly-based multidisciplinary program of scientific research and advanced technological development directed toward maritime applications of new and improved materials, techniques, equipment, systems, and ocean, atmospheric, and space sciences and related technologies.

For more information, please visit www.nrl.navy.mil


Contact:
Donna McKinney
nrl1030@ccs.nrl.navy.mil
202-767-2541

Copyright © U.S. Naval Research Laboratory

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

Gold standards for nanoparticles: Understanding how small organic ions stabilize gold nanoparticles may allow for better control March 29th, 2017

Tiny sensor lays groundwork for precision X-rays detection via endoscopy:Nanoscale fiber-integrated X-ray sensor opens new doors for medical imaging and radiotherapy March 29th, 2017

Researchers uncover secret of nanomaterial that makes harvesting sunlight easier March 29th, 2017

Information storage with a nanoscale twist: Discovery of a novel rotational force inside magnetic vortices makes it easier to design ultrahigh capacity disk drives March 28th, 2017

Spintronics

Smart multi-layered magnetic material acts as an electric switch: New study reveals characteristic of islands of magnetic metals between vacuum gaps, displaying tunnelling electric current March 1st, 2017

First experimental proof of a 70 year old physics theory: First observation of magnetic phase transition in 2-D materials, as predicted by the Nobel winner Onsager in 1943 January 6th, 2017

Investigations of the skyrmion Hall effect reveal surprising results: One step further towards the application of skyrmions in spintronic devices December 28th, 2016

Electron highway inside crystal December 12th, 2016

Chip Technology

Gold standards for nanoparticles: Understanding how small organic ions stabilize gold nanoparticles may allow for better control March 29th, 2017

A big leap toward tinier lines: Self-assembly technique could lead to long-awaited, simple method for making smaller microchip patterns March 27th, 2017

ATTOPSEMI Technology Joins FDXcelerator Program to Deliver Advanced Non-Volatile Memory IP to GLOBALFOUNDRIES 22 FDX® Technology Platform: Leading-edge I-fuse™ brings higher reliability, smaller cell size and ease of programmability for consumer, automotive, and IoT applications March 27th, 2017

Argon is not the 'dope' for metallic hydrogen March 24th, 2017

Sensors

Tiny sensor lays groundwork for precision X-rays detection via endoscopy:Nanoscale fiber-integrated X-ray sensor opens new doors for medical imaging and radiotherapy March 29th, 2017

“Cysteine Rose” Wins 2016 Thermo Fisher Scientific Electron Microscopy Image Contest: Thermo Fisher honors Andrea Jacassi of the Italian Institute of Technology for image of cysteine crystals using focused ion beam techniques March 27th, 2017

UC researchers use gold coating to control luminescence of nanowires: University of Cincinnati physicists manipulate nanowire semiconductors in pursuit of making electronics smaller, faster and cheaper March 17th, 2017

Optical fingerprint can reveal pollutants in the air: Researchers at Chalmers University of Technology have proposed a new, sophisticated method of detecting molecules with sensors based on ultra-thin nanomaterials March 15th, 2017

Discoveries

Gold standards for nanoparticles: Understanding how small organic ions stabilize gold nanoparticles may allow for better control March 29th, 2017

Tiny sensor lays groundwork for precision X-rays detection via endoscopy:Nanoscale fiber-integrated X-ray sensor opens new doors for medical imaging and radiotherapy March 29th, 2017

Researchers uncover secret of nanomaterial that makes harvesting sunlight easier March 29th, 2017

Information storage with a nanoscale twist: Discovery of a novel rotational force inside magnetic vortices makes it easier to design ultrahigh capacity disk drives March 28th, 2017

Announcements

Gold standards for nanoparticles: Understanding how small organic ions stabilize gold nanoparticles may allow for better control March 29th, 2017

Tiny sensor lays groundwork for precision X-rays detection via endoscopy:Nanoscale fiber-integrated X-ray sensor opens new doors for medical imaging and radiotherapy March 29th, 2017

Researchers uncover secret of nanomaterial that makes harvesting sunlight easier March 29th, 2017

Information storage with a nanoscale twist: Discovery of a novel rotational force inside magnetic vortices makes it easier to design ultrahigh capacity disk drives March 28th, 2017

Energy

Gold standards for nanoparticles: Understanding how small organic ions stabilize gold nanoparticles may allow for better control March 29th, 2017

Researchers uncover secret of nanomaterial that makes harvesting sunlight easier March 29th, 2017

Argon is not the 'dope' for metallic hydrogen March 24th, 2017

Rice U. refines filters for greener natural gas: New study defines best materials for carbon capture, methane selectivity March 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