Science Current Events | Science News | Brightsurf.com
 
Email a Friend Send to a friend
Printer Friendly Print Scientists Image 'Magnetic Semiconductors' On The Nanoscale

Scientists Image 'Magnetic Semiconductors' On The Nanoscale

July 27, 2006

In a first-of-its-kind achievement, scientists at the University of Iowa, the University of Illinois at Urbana-Champaign and Princeton University have directly imaged the magnetic interactions between two magnetic atoms less than one nanometer apart (one billionth of a meter) and embedded in a semiconductor chip.

The findings, scheduled for publication as the cover story of the July 27 issue of the journal Nature, bring scientists one step closer toward realizing the goal of building a very advanced semiconductor computer chip. The chip would be based upon a property of the electron called "spin" and the related technology of "spintronics," according to Michael Flatté, professor in the UI College of Liberal Arts and Sciences Department of Physics and Astronomy and leader of the UI research group.




"With spintronics, data manipulation and long-term storage can be conducted in one computer chip, rather than separately in a CPU and a hard drive as currently practiced. The data manipulation could also be done quicker and require less power. Such a computer would be much smaller in size and use less energy," Flatté says.

He adds that some 20 years ago, researchers at IBM discovered that an ordinary semiconducting material, indium arsenide, could be made magnetic at low temperatures by introducing a very small number of magnetic atoms. The magnetic atoms they added were manganese, and soon many other "magnetic semiconductors" were discovered. Gallium arsenide, a semiconductor material used for high-performance devices in cell phones, becomes magnetic when manganese is added, but only at a temperature of -88 C (-126 F). In order for it to be used in future computer chips, magnetic semiconductors like gallium manganese arsenide must remain magnetic at higher temperatures and also be made "cleaner," or less resistant to current flow.

"Visualizing the magnetic interactions on the nanoscale may lead to better magnetic semiconductor materials and applications for them in the electronics industry," says Flatté, who along with UI Assistant Research Scientist Jian-Ming Tang predicted that the magnetic interactions could be imaged with a scanning tunneling microscope. "An electron behaves as if it carries a small magnet around with it. This property, called "spin," has not been used in computer chips to date. If the materials are good enough, then new computer chips that require much less power to run are possible. Even revolutionary 'quantum computers' that use strange quantum phenomena of the atomic world to perform calculations may be possible," says Flatté.

Flatté and Tang had predicted that the magnetic interactions should depend strongly on where in the crystal lattice of the semiconductor the atoms were sitting. Some configurations interacted very strongly and others very weakly. "We thought it would require a lot of luck to see this effect. Usually when manganese is placed in gallium arsenide, it enters the lattice in many different positions. To see two manganese atoms within a nanometer of each other, but isolated from all other manganese, would be statistically very unlikely," he says.

Flatté notes that the team took a completely different approach toward seeing the magnetic interactions. Instead of trusting luck to help them find an arrangement of atoms, they placed the manganese atoms one at a time into a fresh, clean piece of gallium arsenide. "Using the tip of a scanning tunneling microscope, we can take out a single atom from the base material and replace it with a single metal that gives the semiconductor its magnetic properties," says Ali Yazdani, Princeton University physics professor and article co-author. He notes that the effort marks the first time that scientists have achieved this degree of control over the atomic-level structure of a semiconductor. In essence, the team used this unique capability to make a semiconductor magnetic, one atom at a time. "The ability to tailor semiconductors on the atomic scale is the holy grail of electronics, and this method may be the approach that is needed," says Yazdani.

Dale Kitchen, a researcher in Yazdani's lab, hit upon the solution while working with a high-tech tool used to explore complex materials called a scanning tunneling microscope, a device that operates very differently from a desktop optical microscope. The device has a finely-pointed electrical probe that passes over a surface in order to detect variations with a weak electric field. The team, however, found that the charged tip could also be used to eject a single gallium atom from the surface, replacing it with one of manganese that was waiting nearby.

By incorporating manganese atoms into the gallium arsenide semiconductor, the team has created an atomic-scale laboratory that can reveal what researchers have sought for decades: the precise interactions among atoms and electrons in chip materials. The team used their new technique to find the optimal arrangements for manganese atoms that enhance the magnetic properties of gallium manganese arsenide. These arrangements agreed with Flatté and Tang's predictions. "To predict how a material will behave, and then have that prediction dramatically confirmed, as in this experiment, is one of the most enjoyable experiences of research," says Flatté.

Flatté cautions that further advances will be required to translate the new research results into new chip technology and also that using a scanning tunneling microscope to grow large pieces of high quality gallium manganese arsenide may not be practical. However, he says, the lessons learned about optimal arrangements of magnetic atoms in semiconductors will be transferred to other semiconductor growth techniques and to other magnetic semiconductor materials.

The research project was funded in part by the National Science Foundation and the U.S. Army Research Office.

University of Iowa



Related Semiconductor Current Events and Semiconductor News Articles Semiconductor Current Events and Semiconductor News RSS Semiconductor Current Events and Semiconductor News RSS
MIT: Better way to harness waste heat
New MIT research points the way to a technology that might make it possible to harvest much of the wasted heat produced by everything from computer processor chips to car engines to electric powerplants, and turn it into usable electricity.

New study confirms exotic electric properties of graphene
First, it was the soccer-ball-shaped molecules dubbed buckyballs. Then it was the cylindrically shaped nanotubes. Now, the hottest new material in physics and nanotechnology is graphene: a remarkably flat molecule made of carbon atoms arranged in hexagonal rings much like molecular chicken wire.

Small nanoparticles bring big improvement to medical imaging
If you're watching the complex processes in a living cell, it is easy to miss something important-especially if you are watching changes that take a long time to unfold and require high-spatial-resolution imaging.

JQI researchers create entangled photons from quantum dots
To exploit the quantum world to the fullest, a key commodity is entanglement-the spooky, distance-defying link that can form between objects such as atoms even when they are completely shielded from one another.

Working together to design robust silicon chips
Designers of high-speed silicon chips have often had to compromise on performance levels for their integrated circuit designs because of physical weaknesses appearing during design verification or even in production.

Understanding mechanical properties of silicon nanowires paves way for nanodevices
Silicon nanowires are attracting significant attention from the electronics industry due to the drive for ever-smaller electronic devices, from cell phones to computers.

Caltech scientists develop DNA origami nanoscale breadboards for carbon nanotube circuits
In work that someday may lead to the development of novel types of nanoscale electronic devices, an interdisciplinary team of researchers at the California Institute of Technology (Caltech) has combined DNA's talent for self-assembly with the remarkable electronic properties of carbon nanotubes, thereby suggesting a solution to the long-standing problem of organizing carbon nanotubes into nanoscale electronic circuits.

New 'finFET' promising for smaller transistors, more powerful chips
Purdue University researchers are making progress in developing a new type of transistor that uses a finlike structure instead of the conventional flat design, possibly enabling engineers to create faster and more compact circuits and computer chips.

Technology May Cool The Laptop
Does your laptop sometimes get so hot that it can almost be used to fry eggs?

University of Cincinnati researchers create all-electric spintronics
A multidisciplinary team of UC researchers is the first to find an innovative and novel way to control an electron's spin orientation using purely electrical means.
More Semiconductor Current Events and Semiconductor News Articles
The Essential Guide to Semiconductors

The Essential Guide to Semiconductors
by Jim Turley (Author)

Semiconductors are the building blocks of computing. They are the electronic chips that are in every computer and device on the market. Cellphones, cars, computers (of all kinds), gaming systems, machines - anything with hardware has an electronic (or semiconductor) component. This is the professional's guide to the business and technology of semiconductor design and manufacturing. The semiconductor industry lends itself very well to a book of this kind. Just as the telecommunications area, the semiconductor industry is broad and complicated. There's a definite need for a book that explains the in's and out's of the technology and how it works - without bogging down readers with too much technical content.

Semiconductor Device Fundamentals

Semiconductor Device Fundamentals
by Robert F. Pierret (Author)

Introduces and explains the basic terminology, models, properties, and concepts associated with semiconductors and semiconductor devices. Systematically develops the analytical tools needed to solve practical device problems. DLC: Semiconductors.

Physics of Semiconductor Devices

Physics of Semiconductor Devices
by Simon M. Sze (Author), Kwok K. Ng (Author)

The Third Edition of the standard textbook and reference in the field of semiconductor devices

This classic book has set the standard for advanced study and reference in the semiconductor device field. Now completely updated and reorganized to reflect the tremendous advances in device concepts and performance, this Third Edition remains the most detailed and exhaustive single source of information on the most important semiconductor devices. It gives readers immediate access to detailed descriptions of the underlying physics and performance characteristics of all major bipolar, field-effect, microwave, photonic, and sensor devices.

Designed for graduate textbook adoptions and reference needs, this new edition includes: A complete update of the latest...

Handbook of Semiconductor Manufacturing Technology, Second Edition

Handbook of Semiconductor Manufacturing Technology, Second Edition
by Robert Doering (Editor), Yoshio Nishi (Editor)

Retaining the comprehensive and in-depth approach that cemented the bestselling first edition's place as a standard reference in the field, the Handbook of Semiconductor Manufacturing Technology, Second Edition features new and updated material that keeps it at the vanguard of today's most dynamic and rapidly growing field. Iconic experts Robert Doering and Yoshio Nishi have again assembled a team of the world's leading specialists in every area of semiconductor manufacturing to provide the most reliable, authoritative, and industry-leading information available.

Stay Current with the Latest Technologies
In addition to updates to nearly every existing chapter, this edition features five entirely new contributions on…
Silicon-on-insulator (SOI) materials and...

On Semiconductor General Purpose NPN Leaded Transistor TO-92 BULK (Bag of 10)

On Semiconductor General Purpose NPN Leaded Transistor TO-92 BULK (Bag of 10)
by On Semiconductor

On Semiconductor General Purpose NPN Leaded Transistor TO-92 BULK (Bag of 10)

Semiconductor Material and Device Characterization

Semiconductor Material and Device Characterization
by Dieter K. Schroder (Author)

This Third Edition updates a landmark text with the latest findings

The Third Edition of the internationally lauded Semiconductor Material and Device Characterization brings the text fully up-to-date with the latest developments in the field and includes new pedagogical tools to assist readers. Not only does the Third Edition set forth all the latest measurement techniques, but it also examines new interpretations and new applications of existing techniques.

Semiconductor Material and Device Characterization remains the sole text dedicated to characterization techniques for measuring semiconductor materials and devices. Coverage includes the full range of electrical and optical characterization methods, including the more specialized chemical and physical techniques....

Semiconductor Manufacturing Technology

Semiconductor Manufacturing Technology
by Michael Quirk (Author), Julian Serda (Author)

For the introductory course in Semiconductor Manufacturing Technology. This text introduces the terminology, concepts, processes, products, and equipment commonly used in the manufacture of ultra-large-scale integrated (ULSI) semiconductors. The book provides helpful, up-to-date technical information about semiconductor manufacturing and strikes an effective balance between the process and equipment technology found in wafer fabrications.

The Physics of Semiconductors: An Introduction Including Devices and Nanophysics

The Physics of Semiconductors: An Introduction Including Devices and Nanophysics
by Marius Grundmann (Author)

The Physics of Semiconductors provides material for a comprehensive upper-level-undergraduate and graduate course on the subject, guiding readers to the point where they can choose a special topic and begin supervised research. The textbook provides a balance between essential aspects of solid-state and semiconductor physics, on the one hand, and the principles of various semiconductor devices and their applications in electronic and photonic devices, on the other. It highlights many practical aspects of semiconductors such as alloys, strain, heterostructures, nanostructures, that are necessary in modern semiconductor research but typically omitted in textbooks. For the interested reader some additional advanced topics are included, such as Bragg mirrors, resonators, polarized and...

Worlds in Flux

Worlds in Flux
Starring: Semiconductor



On Semiconductor General Purpose PNP Leaded Transistor TO-92 BULK (Bag of 10)

On Semiconductor General Purpose PNP Leaded Transistor TO-92 BULK (Bag of 10)
by On Semiconductor

On Semiconductor General Purpose PNP Leaded Transistor TO-92 BULK (Bag of 10)

© 2009 BrightSurf.com