 |
|
Scientists build 'magnetic semiconductors' one atom at a time
July 28, 2006Princeton, N.J. - In a stride that could hasten the development of computer chips that both calculate and store data, a team of Princeton scientists has turned semiconductors into magnets by the precise placement of metal atoms within a material from which chips are made.
The effort marks the first time that scientists have achieved this degree of control over the atomic-level structure of a semiconductor, a goal that has eluded researchers for many years. The team used this unique capability to make a semiconductor magnetic, one atom at a time. Team leader Ali Yazdani said that manipulating semiconductors could eventually revolutionize computers by exploiting not just the flow of electrons but also their quantum property, called spin, for computation.
"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," said Yazdani, a Princeton professor of physics. "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."
The team, which also includes scientists from the University of Illinois at Urbana-Champaign and the University of Iowa as well as Princeton, will publish their results as the cover article of the July 27 issue of the scientific journal, Nature.
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 material. The team used their new technique to find the optimal arrangements for manganese atoms that can enhance the magnetic properties of gallium arsenide. Implementation of their findings within the chip manufacturing process could result in a major advance in the use of both the magnetic "spin" as well as electric charge for computation.
"Chips might take on many new capabilities once such 'spintronic' technology is perfected," Yazdani said. "One thing we might be able to do is make chips that can both manipulate data and store it as well, which right now generally requires two separate parts of a computer working together."
Computers use two different kinds of technology to calculate results and store data. While semiconductor chips - often based on silicon or more advanced materials such as gallium arsenide - do the calculating, data storage has generally been accomplished with magnetic materials within floppy disks or reels of tape. Combining these functions into a single device could reduce the size and energy requirements of computer hardware, a perennial goal of the industry.
Although gallium arsenide "doped" with manganese has been a promising candidate material for such dual-function chips for a decade, working with the material has proven frustrating for a number of reasons. One difficulty is that researchers have not been able to engineer the material with optimal magnetic properties.
"Up until now, we have not had a way to control how the manganese sits in the gallium arsenide substrate," Yazdani said. "We could not specify, for example, how large the bits of manganese would be, or how far apart they would be located. And because we couldn't study how changing these variables affected the semiconductor's performance, it was hard to know what its ideal specifications should be. For the most part, we had to just crystallize the material - with the dopant arranged more or less randomly - and hope."
Dale Kitchen, a reasearcher in Yazdani's lab and first author of the Nature paper, hit upon a solution while working with a high-tech tool used to explore complex materials called a scanning tunneling microscope, which operates very differently than 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.
"The important thing technically was that we could incorporate the manganese into the underlying crystal lattice," Yazdani said. "If you want to study how the semiconductor functions, it would not have been enough merely to deposit the manganese on the surface. They needed to become a single integrated material."
Using their new technique, the team was able to find the precise arrangements of manganese atoms that exhibited magnetic properties, the important factor in developing spin-based electronics. The experimental data agreed with theoretical work that had been performed by Michael Flatté and his group at the University of Iowa, which had anticipated the atomic arrangement that optimized magnetism in the experiments.
Yazdani cautioned that his team's technique would not translate immediately into new chip technology but would benefit fundamental research by providing a testbed for exploring magnetism in other semiconductors.
"We can now ask questions about these magnetic atoms and get answers," he said. "How does it affect the semiconductors' performance when you change their orientation, for example, or their distance from one another? Answers to these questions may allow us to link the electric current and magnetic spin within these new semiconductors, and that's a goal the field has been seeking for many years."
Princeton University
The team, which also includes scientists from the University of Illinois at Urbana-Champaign and the University of Iowa as well as Princeton, will publish their results as the cover article of the July 27 issue of the scientific journal, Nature.
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 material. The team used their new technique to find the optimal arrangements for manganese atoms that can enhance the magnetic properties of gallium arsenide. Implementation of their findings within the chip manufacturing process could result in a major advance in the use of both the magnetic "spin" as well as electric charge for computation.
"Chips might take on many new capabilities once such 'spintronic' technology is perfected," Yazdani said. "One thing we might be able to do is make chips that can both manipulate data and store it as well, which right now generally requires two separate parts of a computer working together."
Computers use two different kinds of technology to calculate results and store data. While semiconductor chips - often based on silicon or more advanced materials such as gallium arsenide - do the calculating, data storage has generally been accomplished with magnetic materials within floppy disks or reels of tape. Combining these functions into a single device could reduce the size and energy requirements of computer hardware, a perennial goal of the industry.
Although gallium arsenide "doped" with manganese has been a promising candidate material for such dual-function chips for a decade, working with the material has proven frustrating for a number of reasons. One difficulty is that researchers have not been able to engineer the material with optimal magnetic properties.
"Up until now, we have not had a way to control how the manganese sits in the gallium arsenide substrate," Yazdani said. "We could not specify, for example, how large the bits of manganese would be, or how far apart they would be located. And because we couldn't study how changing these variables affected the semiconductor's performance, it was hard to know what its ideal specifications should be. For the most part, we had to just crystallize the material - with the dopant arranged more or less randomly - and hope."
Dale Kitchen, a reasearcher in Yazdani's lab and first author of the Nature paper, hit upon a solution while working with a high-tech tool used to explore complex materials called a scanning tunneling microscope, which operates very differently than 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.
"The important thing technically was that we could incorporate the manganese into the underlying crystal lattice," Yazdani said. "If you want to study how the semiconductor functions, it would not have been enough merely to deposit the manganese on the surface. They needed to become a single integrated material."
Using their new technique, the team was able to find the precise arrangements of manganese atoms that exhibited magnetic properties, the important factor in developing spin-based electronics. The experimental data agreed with theoretical work that had been performed by Michael Flatté and his group at the University of Iowa, which had anticipated the atomic arrangement that optimized magnetism in the experiments.
Yazdani cautioned that his team's technique would not translate immediately into new chip technology but would benefit fundamental research by providing a testbed for exploring magnetism in other semiconductors.
"We can now ask questions about these magnetic atoms and get answers," he said. "How does it affect the semiconductors' performance when you change their orientation, for example, or their distance from one another? Answers to these questions may allow us to link the electric current and magnetic spin within these new semiconductors, and that's a goal the field has been seeking for many years."
Princeton University
Semiconductor Current Events and Semiconductor News RSSTechnology 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.
Transforming Nanowires Into Nano-Tools Using Cation Exchange Reactions
A team of engineers from the University of Pennsylvania has transformed simple nanowires into reconfigurable materials and circuits, demonstrating a novel, self-assembling method for chemically creating nanoscale structures that are not possible to grow or obtain otherwise.
Caltech scientists first to trap light and sound vibrations together in nanocrystal
Researchers at the California Institute of Technology (Caltech) have created a nanoscale crystal device that, for the first time, allows scientists to confine both light and sound vibrations in the same tiny space.
Rutgers physicists discover novel electronic properties in two-dimensional carbon structure
Rutgers researchers have discovered novel electronic properties in two-dimensional sheets of carbon atoms called graphene that could one day be the heart of speedy and powerful electronic devices.
Small ... smaller ... smallest? ASU researchers create molecular diode
Recently, at Arizona State University's Biodesign Institute, N.J. Tao and collaborators have found a way to make a key electrical component on a phenomenally tiny scale. Their single-molecule diode is described in this week's online edition of Nature Chemistry.
MU Researchers Create Smaller and More Efficient Nuclear Battery
Batteries can power anything from small sensors to large systems. While scientists are finding ways to make them smaller but even more powerful, problems can arise when these batteries are much larger and heavier than the devices themselves. University of Missouri researchers are developing a nuclear energy source that is smaller, lighter and more efficient.
Color sensors for better vision
The car of the future will have lots of smart assistants onboard - helping to park the car, recognize traffic signs and to warn the driver of blind spot hazards.
U-M physicists create first atomic-scale map of quantum dots
University of Michigan physicists have created the first atomic-scale maps of quantum dots, a major step toward the goal of producing "designer dots" that can be tailored for specific applications.
Discovery Brings New Type of Fast Computers Closer to Reality
Physicists at UC San Diego have successfully created speedy integrated circuits with particles called "excitons" that operate at commercially cold temperatures, bringing the possibility of a new type of extremely fast computer based on excitons closer to reality.
More Semiconductor Current Events and Semiconductor News Articles
 |
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 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 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 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... |
 |
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. |
 |
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.... |
 |
Fundamentals of Semiconductor Manufacturing and Process Control by Gary S. May (Author), Costas J. Spanos (Author) A practical guide to semiconductor manufacturing from process control to yield modeling and experimental design Fundamentals of Semiconductor Manufacturing and Process Control covers all issues involved in manufacturing microelectronic devices and circuits, including fabrication sequences, process control, experimental design, process modeling, yield modeling, and CIM/CAM systems. Readers are introduced to both the theory and practice of all basic manufacturing concepts. Following an overview of manufacturing and technology, the text explores process monitoring methods, including those that focus on product wafers and those that focus on the equipment used to produce wafers. Next, the text sets forth some fundamentals of statistics and yield modeling, which... |
 |
Principles of Semiconductor Devices (The Oxford Series in Electrical and Computer Engineering) by Sima Dimitrijev (Author) Quantum mechanical phenomena-including energy bands, energy gaps, holes, and effective mass-constitute the majority of properties unique to semiconductor materials. Understanding how these properties affect the electrical characteristics of semiconductors is vital for engineers working with today's nanoscale devices. Designed for upper-level undergraduate and graduate courses, Principles of Semiconductor Devices covers the dominant practical applications of semiconductor device theory and applies quantum mechanical concepts and equations to develop the energy-band model. The text presents quantum mechanics through examples related to the energy-band model, providing students with a deeper understanding of the energy-band diagrams used to explain semiconductor device operation. The... |
 |
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... |
 |
Semiconductor Devices: Physics and Technology, 2nd Edition by Simon M. Sze (Author) This book is an introduction to the physical principles of modern semiconductor devices and their advanced fabrication technology. It begins with a brief historical review of major devices and key technologies and is then divided into three sections: semiconductor material properties, physics of semiconductor devices and processing technology to fabricate these semiconductor devices. |
| © 2009 BrightSurf.com |