Science Current Events | Science News | Brightsurf.com
 
Email a Friend Send to a friend
Printer Friendly Print Nanotube forests grown on silicon chips for future computers, electronics
Slashdot It! Slashdot Nanotube forests grown on silicon chips for future computers, electronics
Submit to Reddit Submit Nanotube forests grown on silicon chips for future computers, electronics to Reddit
Reading: Nanotube forests grown on silicon chips for future computers, electronicsTwitter This Reading: Nanotube forests grown on silicon chips for future computers, electronicsTwitter Nanotube forests grown on silicon chips for future computers, electronics
Add to Facebook Add Nanotube forests grown on silicon chips for future computers, electronics to Facebook

Nanotube forests grown on silicon chips for future computers, electronics

October 02, 2007

Engineers have shown how to grow forests of tiny cylinders called carbon nanotubes onto the surfaces of computer chips to enhance the flow of heat at a critical point where the chips connect to cooling devices called heat sinks.

The carpetlike growth of nanotubes has been shown to outperform conventional "thermal interface materials." Like those materials, the nanotube layer does not require elaborate clean-room environments, representing a possible low-cost manufacturing approach to keep future chips from overheating and reduce the size of cooling systems, said Placidus B. Amama, a postdoctoral research associate at the Birck Nanotechnology Center in Purdue's Discovery Park.




Researchers are trying to develop new types of thermal interface materials that conduct heat more efficiently than conventional materials, improving overall performance and helping to meet cooling needs of future chips that will produce more heat than current microprocessors. The materials, which are sandwiched between silicon chips and the metal heat sinks, fill gaps and irregularities between the chip and metal surfaces to enhance heat flow between the two.

The method developed by the Purdue researchers enables them to create a nanotube interface that conforms to a heat sink's uneven surface, conducting heat with less resistance than comparable interface materials currently in use by industry, said doctoral student Baratunde A. Cola.

Findings were detailed in a research paper that appeared in September's issue of the journal Nanotechnology. The paper was written by Amama; Cola; Timothy D. Sands, director of the Birck Nanotechnology Center and the Basil S. Turner Professor of Materials Engineering and Electrical and Computer Engineering; and Xianfan Xu and Timothy S. Fisher, both professors of mechanical engineering.

Better thermal interface materials are needed either to test computer chips in manufacturing or to keep chips cooler during operation in commercial products.

"In a personal computer, laptop and portable electronics, the better your thermal interface material, the smaller the heat sink and overall chip-cooling systems have to be," Cola said.

Heat sinks are structures that usually contain an array of fins to increase surface contact with the air and improve heat dissipation, and a fan often also is used to blow air over the devices to cool chips.

Conventional thermal interface materials include greases, waxes and a foil made of a metal called indium. All of these materials, however, have drawbacks. The greases don't last many cycles of repeatedly testing chips on the assembly line. The indium foil doesn't make good enough contact for optimum heat transfer, Fisher said.

The Purdue researchers created templates from branching molecules called dendrimers, forming these templates on a silicon surface. Then, metal catalyst particles that are needed to grow the nanotubes were deposited inside cavities between the dendrimer branches. Heat was then applied to the silicon chip, burning away the polymer and leaving behind only the metal catalyst particles.

The engineers then placed the catalyst particle-laden silicon inside a chamber and exposed it to methane gas. Microwave energy was applied to break down the methane, which contains carbon. The catalyst particles prompted the nanotubes to assemble from carbon originating in the methane, and the tubes then grew vertically from the surface of the silicon chip.

"The dendrimer is a vehicle to deliver the cargo of catalyst particles, making it possible for us to seed the carbon nanotube growth right on the substrate," Amama said. "We are able to control the particle size - what ultimately determines the diameters of the tubes - and we also have control over the density, or the thickness of this forest of nanotubes. The density, quality and diameter are key parameters in controlling the heat-transfer properties."

The catalyst particles are made of "transition metals," such as iron, cobalt, nickel or palladium. Because the catalyst particles are about 10 nanometers in diameter, they allow the formation of tubes of similar diameter.

The branching dendrites are tipped with molecules called amines, which act as handles to stick to the silicon surface.

"This is important because for heat-transfer applications, you want the nanotubes to be well-anchored," Amama said.

Researchers usually produce carbon nanotubes separately and then attach them to the silicon chips or mix them with a polymer and then apply them as a paste.

"Our direct growth approach, however, addresses the critical heat-flow path, which is between the chip surface and the nanotubes themselves," Fisher said. "Without this direct connection, the thermal performance suffers greatly."

Because the dendrimers have a uniform composition and structure, the researchers were able to control the distribution and density of catalyst particles.

The research team also has been able to control the number of "defect sites" in the lattice of carbon atoms making up the tubes, creating tubes that are more flexible. This increased flexibility causes the nanotube forests to conform to the surface of the heat sink, making for better contact and improved heat conduction.

"The tubes bend like toothbrush bristles, and they stick into the gaps and make a lot of real contact," Cola said.

The carbon nanotubes were grown using a technique called microwave plasma chemical vapor deposition, a relatively inexpensive method for manufacturing a thermal-interface material made of carbon nanotubes, Fisher said.

"The plasma deposition approach allows us great flexibility in controlling the growth environment and has enabled us to grow carbon nanotube arrays over a broad range of substrate temperatures," Fisher said.

The research has been funded by NASA through the Institute for Nanoelectronics and Computing, based at Purdue's Discovery Park. Cola also received support through a fellowship from Intel Corp. and Purdue.

Purdue University





Science News and Science Current Events Tag Cloud
This tag cloud is a visual representation of term frequencies of random science news topics with common terms grouped together and emphasized by their display size.
Hygiene   Asteroids   Appendicitis   RNA   Kidney Cancer   Cox-2 Inhibitors   Smokers   Malaria parasite   Cancer Drug   Antioxidants   Brain Disease   Climate Model   Prostate Cancer   Myocardial Infarction   Melanoma   Leukaemia   Synapses   Quasar   Alcohol Dependence   Flu Virus   Huntingtons Disease   Sea Urchin   Cancer Treatment   Malaria Vaccine   Butterflies  
Related Carbon Nanotubes Current Events and Carbon Nanotubes News Articles Carbon Nanotubes Current Events and Carbon Nanotubes News RSS Carbon Nanotubes Current Events and Carbon Nanotubes News RSS
Feather fibers fluff up hydrogen storage capacity
Scientists in Delaware say they have developed a new hydrogen storage method - carbonized chicken feather fibers - that can hold vast amounts of hydrogen, a promising but difficult to corral fuel source, and do it at a far lower cost than other hydrogen storage systems under consideration.

Penn materials scientist finds plumber's wonderland on graphene
Engineers from the University of Pennsylvania, Sandia National Laboratories and Rice University have demonstrated the formation of interconnected carbon nanostructures on graphene substrate in a simple assembly process that involves heating few-layer graphene sheets to sublimation using electric current that may eventually lead to a new paradigm for building integrated carbon-based devices.

Biomimetic-engineering design can replace spaghetti tangle of nanotubes in thermal materials
Nanoelectromechanical systems (NEMS) devices have the potential to revolutionize the world of sensors: motion, chemical, temperature, etc. But taking electromechanical devices from the micro scale down to the nano requires finding a means to dissipate the heat output of this tiny gadgetry.

Inexpensive plastic used in CDs could improve aircraft, computer electronics
If one University of Houston professor has his way, the inexpensive plastic now used to manufacture CDs and DVDs will one day soon be put to use in improving the integrity of electronics in aircraft, computers and iPhones.

UCLA researchers develop new method for producing transparent conductors
Researchers at UCLA have developed a new method for producing a hybrid graphene-carbon nanotube, or G-CNT, for potential use as a transparent conductor in solar cells and consumer electronic devices.

New nanotube coating enables novel laser power meter
The U.S. military can now calibrate high-power laser systems, such as those intended to defuse unexploded mines, more quickly and easily thanks to a novel nanotube-coated power measurement device developed at the National Institute of Standards and Technology (NIST).

UCLA physicists create world's smallest incandescent lamp
In an effort to explore the boundary between thermodynamics and quantum mechanics - two fundamental yet seemingly incompatible theories of physics - a team from the UCLA Department of Physics and Astronomy has created the world's smallest incandescent lamp.

Sandia researchers construct carbon nanotube device that can detect colors of the rainbow
Researchers at Sandia National Laboratories have created the first carbon nanotube device that can detect the entire visible spectrum of light, a feat that could soon allow scientists to probe single molecule transformations, study how those molecules respond to light, observe how the molecules change shapes, and understand other fundamental interactions between molecules and nanotubes.

Rice researchers unzip the future
Scientists at Rice University have found a simple way to create basic elements for aircraft, flat-screen TVs, electronics and other products that incorporate sheets of tough, electrically conductive material.

Nanoribbons from sliced open nanotubes: new, faster, more accurate method from Stanford
A world of potential may lie tied up in graphene nanoribbons, particularly for electronics applications. But researchers have been hampered in their efforts to fully explore that potential because they had no reliable way of creating the large quantities of uniform nanoribbons needed to conduct extensive studies.
More Carbon Nanotubes Current Events and Carbon Nanotubes News Articles
Carbon Nanotubes: Properties and Applications

Carbon Nanotubes: Properties and Applications
by Michael J. O'Connell (Editor)

Since their discovery more than a decade ago, carbon nanotubes (CNTs) have held scientists and engineers in captive fascination, seated on the verge of enormous breakthroughs in areas such as medicine, electronics, and materials science, to name but a few. Taking a broad look at CNTs and the tools used to study them, Carbon Nanotubes: Properties and Applications comprises the efforts of leading nanotube researchers led by Michael O’Connell, protégé of the late father of nanotechnology, Richard Smalley. Each chapter is a self-contained treatise on various aspects of CNT synthesis, characterization, modification, and applications.

The book opens with a general introduction to the basic characteristics and the history of CNTs, followed by discussions on synthesis methods and the...

Carbon Nanotubes: Advanced Topics in the Synthesis, Structure, Properties and Applications

Carbon Nanotubes: Advanced Topics in the Synthesis, Structure, Properties and Applications
by Springer

The carbon nanotubes field has evolved substantially since the publication of the bestseller Carbon Nanotubes: Synthesis, Structure, Properties and Applications . The present volume builds on the generic aspects of the aforementioned book, which emphasizes the fundamentals, with the new volume emphasizing areas that have grown rapidly since the first volume, guiding future directions where research is needed and highlighting applications. The volume also includes an emphasis on areas like graphene, other carbon-like and other tube-like materials because these fields are likely to affect and influence developments in nanotubes in the next 5 years.



Easton MonkeyLite DH CNT Carbon Fiber MTB Riser Bicycle Handlebar (31.8mm Diameter, 711mm Wide, 40mm Rise)

Easton MonkeyLite DH CNT Carbon Fiber MTB Riser Bicycle Handlebar (31.8mm Diameter, 711mm Wide, 40mm Rise)
by Easton

New carbon unidirectional design

Carbon Nanotube Science: Synthesis, Properties and Applications

Carbon Nanotube Science: Synthesis, Properties and Applications
by Peter J. F. Harris (Author)

Carbon nanotubes represent one of the most exciting research areas in modern science. These molecular-scale carbon tubes are the stiffest and strongest fibres known, with remarkable electronic properties, and potential applications in a wide range of fields. Carbon Nanotube Science is the most concise, accessible book for the field, presenting the basic knowledge that graduates and researchers need to know. Based on the successful Carbon Nanotubes and Related Structures, this new book focuses solely on carbon nanotubes, covering the major advances made in recent years in this rapidly developing field. Chapters focus on electronic properties, chemical and bimolecular functionalisation, nanotube composites and nanotube-based probes and sensors. The book begins with a comprehensive...

Carbon Nanotubes: Science and Applications

Carbon Nanotubes: Science and Applications
by CRC Press

No description available

Carbon Nanotubes: Advanced Topics in the Synthesis, Structure, Properties and Applications (Topics in Applied Physics)

Carbon Nanotubes: Advanced Topics in the Synthesis, Structure, Properties and Applications (Topics in Applied Physics)
by Ado Jorio (Author), Ado Jorio (Editor), Gene Dresselhaus (Editor), Mildred S. Dresselhaus (Editor)

The carbon nanotubes field has evolved substantially since the publication of the bestseller Carbon Nanotubes: Synthesis, Structure, Properties and Applications . The present volume builds on the generic aspects of the aforementioned book, which emphasizes the fundamentals, with the new volume emphasizing areas that have grown rapidly since the first volume, guiding future directions where research is needed and highlighting applications. The volume also includes an emphasis on areas like graphene, other carbon-like and other tube-like materials because these fields are likely to affect and influence developments in nanotubes in the next 5 years.



Easton MonkeyLite XC CNT Carbon Fiber MTB Riser Bicycle Handlebar (660mm Wide, 40mm Rise)

Easton MonkeyLite XC CNT Carbon Fiber MTB Riser Bicycle Handlebar (660mm Wide, 40mm Rise)
by Easton

Low and high rise (8° sweep | 4° upsweep)

Carbon Nanotubes: Basic Concepts and Physical Properties

Carbon Nanotubes: Basic Concepts and Physical Properties
by Stephanie Reich (Author), Christian Thomsen (Author), Janina Maultzsch (Author)

Carbon nanotubes are exceptionally interesting from a fundamental research point of view. Many concepts of one-dimensional physics have been verified experimentally such as electron and phonon confinement or the one-dimensional singularities in the density of states; other 1D signatures are still under debate, such as Luttinger-liquid behavior. Carbon nanotubes are chemically stable, mechanically very strong, and conduct electricity. For this reason, they open up new perspectives for various applications, such as nano-transistors in circuits, field-emission displays, artificial muscles, or added reinforcements in alloys.

This text is an introduction to the physical concepts needed for investigating carbon nanotubes and other one-dimensional solid-state systems. Written for...

Applied Physics of Carbon Nanotubes: Fundamentals of Theory, Optics and Transport Devices

Applied Physics of Carbon Nanotubes: Fundamentals of Theory, Optics and Transport Devices
by Springer

The book describes the state-of-the-art in fundamental, applied and device physics of nanotubes, including fabrication, manipulation and characterization for device applications; optics of nanotubes; transport and electromechanical devices and fundamentals of theory for applications. This information is critical to the field of nanoscience since nanotubes have the potential to become a very significant electronic material for decades to come. The book will benefit all all readers interested in the application of nanotubes, either in their theoretical foundations or in newly developed characterization tools that may enable practical device fabrication.



Physical Properties of Carbon Nanotubes

Physical Properties of Carbon Nanotubes
by R. Saito (Author)

This text is intended for researchers who want to perform theoretical analysis of carbon nanotubes. It can be used by graduate students in a solid state physics to learn how to investigate the structure of carbon nanotubes, its electronic and vibrational properties.

© 2009 BrightSurf.com