Featured Research

from universities, journals, and other organizations

Scientists Control The Spin Of Semiconductor Quantum Dot Shell States

Date:
February 10, 2009
Source:
Naval Research Laboratory
Summary:
Scientists have recently demonstrated the ability to control the spin population of the individual quantum shell states of self-assembled indium arsenide quantum dots (QDs). These results are significant in the understanding of QD behavior and scientists' ability to utilize QDs in active devices or for information processing.

Atomic force microscope image of the uncovered QDs.
Credit: Naval Research Laboratory

Scientists at the Naval Research Laboratory (NRL) have recently demonstrated the ability to control the spin population of the individual quantum shell states of self-assembled indium arsenide (InAs) quantum dots (QDs). These results are significant in the understanding of QD behavior and scientists' ability to utilize QDs in active devices or for information processing.

The scientists, from NRL's Materials Science and Technology Division, used a spin-polarized bias current from an iron (Fe) thin film contact and determined the strength of the interaction between spin-polarized electrons in the s, p and d shells.

Semiconductor QDs are nanoscale circular disks of one semiconducting material, typically 3 nm high by 30 nm in diameter, embedded within layers of a second material. Figure 1 shows such a structure, with an atomic force microscope image of the uncovered QDs in figure 2. Semiconductor QDs are attractive for a variety of quantum information processing, electronic and spintronic applications. In spintronic applications, the electron's spin rather than charge is used to store and process information. The International Technology Roadmap for Semiconductors has identified the electron's spin as a new state variable which should be explored as an alternative to the electron's charge for use beyond standard CMOS technology. The QD electronic structure exhibits the s,p,d,f shells characteristic of single atoms, so they are often referred to as "artificial atoms."

The NRL researchers monitor the shell population and spin polarization by measuring the polarized light emitted as a function of the bias current from the Fe contact. In contrast with previous work, they resolve features in the electroluminescence (EL) spectra associated with the individual quantum levels (s-, p-, d-, and f- shells). As the bias current is increased, the shell states fill, and the EL from the QDs exhibits peaks characteristic of the shell energies, as labeled in figure 3.

Intershell exchange strongly modifies the optical polarization observed from that expected for simple models of shell occupation. From a detailed analysis of the EL spectra, the NRL researchers were able to obtain the first experimental measure of the exchange energies between electrons in the s- and p-shells, and between electrons in the p- and d-shells. These energies describe the degree of interaction between these quantum levels.

A complete description of this work can be found in Physical Review Letters (28 November 2008).


Story Source:

The above story is based on materials provided by Naval Research Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

Naval Research Laboratory. "Scientists Control The Spin Of Semiconductor Quantum Dot Shell States." ScienceDaily. ScienceDaily, 10 February 2009. <www.sciencedaily.com/releases/2009/02/090205120403.htm>.
Naval Research Laboratory. (2009, February 10). Scientists Control The Spin Of Semiconductor Quantum Dot Shell States. ScienceDaily. Retrieved April 18, 2014 from www.sciencedaily.com/releases/2009/02/090205120403.htm
Naval Research Laboratory. "Scientists Control The Spin Of Semiconductor Quantum Dot Shell States." ScienceDaily. www.sciencedaily.com/releases/2009/02/090205120403.htm (accessed April 18, 2014).

Share This



More Matter & Energy News

Friday, April 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Small Reactors Could Be Future of Nuclear Energy

Small Reactors Could Be Future of Nuclear Energy

AP (Apr. 17, 2014) After the Fukushima nuclear disaster, the industry fell under intense scrutiny. Now, small underground nuclear power plants are being considered as the possible future of the nuclear energy. (April 17) Video provided by AP
Powered by NewsLook.com
Honda's New ASIMO Robot, More Human-Like Than Ever

Honda's New ASIMO Robot, More Human-Like Than Ever

AFP (Apr. 17, 2014) It walks and runs, even up and down stairs. It can open a bottle and serve a drink, and politely tries to shake hands with a stranger. Meet the latest ASIMO, Honda's humanoid robot. Duration: 00:54 Video provided by AFP
Powered by NewsLook.com
German Researchers Crack Samsung's Fingerprint Scanner

German Researchers Crack Samsung's Fingerprint Scanner

Newsy (Apr. 16, 2014) German researchers have used a fake fingerprint made from glue to bypass the fingerprint security system on Samsung's new Galaxy S5 smartphone. Video provided by Newsy
Powered by NewsLook.com
Porsche CEO Says Supercar Is Not Dead: Cue the Spyder 918

Porsche CEO Says Supercar Is Not Dead: Cue the Spyder 918

TheStreet (Apr. 16, 2014) The Porsche Spyder 918 proves that, in an automotive world obsessed with fuel efficiency, the supercar is not dead. Porsche North America CEO Detlev von Platen attributes the brand's consistent sales growth -- 21% in 2013 -- with an investment in new technology and expanded performance dynamics. The hybrid Spyder 918 has 887 horsepower and 944 lb-ft of torque, but it can run 18 miles on just an electric charge. The $845,000 vehicle is not a consumer-targeted vehicle but a brand statement. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins