Nanotech: Hot Technology Gets a Cool Down

Jun 03, 2008

It’s the hottest technology – featherweight laptops that feature rapid response, crisp graphics and operate complex computer games; slim cell phones with Web-browsing capabilities, store high resolution photos and keep track of our lives; credit card-sized MP3 players that store thousands of songs and hours of videos.

But as those gadgets get smaller, more portable, and are asked to do more, they are getting hotter – as in overheating. Electronic appliances that once were large enough to be cooled by fans are now in danger of malfunctioning because there is no easy way to remove all the excess heat produces by large numbers of tiny transistors operating inside them.

“It’s a major problem that could limit the ability to make all electronics smaller and at the same time faster and more powerful,” said Alexander Balandin, a UCR professor of electrical engineering.

To that end, Balandin recently received a $600,000 grant to help devise such technology. The three-year project, funded by the Air Force Office of Scientific Research (AFOSR), aims to increase the speed of the next generation of electronic and optoelectronic devices while simultaneously reducing heat dissipation and improving thermal management.

Balandin work in this area focuses on phonon engineering, an area of research that he pioneered more than a decade ago.

In tech talk, acoustic phonons are quantized modes of crystal lattice vibrations, which limit electrical conductivity of semiconductors while, at the same time, carry heat in semiconductors and electrical insulators. Optical phonons strongly influence the light emission properties of materials. Nanometer scale dimensions of the state-of-the-art semiconductor devices and a wide variety of available constituent materials allow one to tune the phonon energy dispersion and, thus, control the ways phonons interact with electrons and other phonons.

The methods of controlling the acoustic phonon interaction with electrons may have a strong impact on how much heat is generated in electronic and optoelectronic devices. Examples of optoelectronic devices include light-emitting diodes (LEDs) used in color displays and traffic lights; photodetectors essential for light-wave long-distance telecommunications; semiconductor lasers widely utilized in medical instrumentation, digital data storage, material processing and safety equipment. As these devices continue to be made smaller and the amount of dissipated power per unit area increases their cooling becomes crucial for continuous use.

Balandin uses the following analogy to describe the motion of electrons through a transistor: A large group of students wearing blue T-shirts – they are the electrons – must, quickly and efficiently, move into a room through one door and out of the room through another door located on the other side of the room. Students in red T-shirts – they are the phonons – are in the room bumping into the blue T-shirt students and – occasionally – the walls of the room. As the size of the room decreases things get more chaotic with more bumping (e.g. scattering in scientific terms). The resulting effect is decreased ability of electrons to move through the transistor channel and increased temperature.

Balandin and his researchers will investigate the use of layers of synthetic diamond incorporated with the conventional silicon layers to better manage the interaction of phonons and electrons. Diamond is known to be an excellent thermal conductor and its use in device structures for increasing electron mobility will simultaneously improve the heat removal.

Balandin is the director of the Nano-Device Laboratory, which conducts experimental and theoretical research aimed at better understanding phonons in novel materials, nanostructures and devices.

Source: University of California, Riverside

Explore further: For electronics beyond silicon, a new contender emerges

add to favorites email to friend print save as pdf

Related Stories

Astronomers pinpoint 'Venus Zone' around stars

2 hours ago

San Francisco State University astronomer Stephen Kane and a team of researchers presented today the definition of a "Venus Zone," the area around a star in which a planet is likely to exhibit the unlivable ...

History books becoming next fight in Texas schools

3 hours ago

The next ideological fight over new textbooks for Texas classrooms intensified Wednesday with critics lambasting history lessons that they say exaggerate the influence of Moses in American democracy and negatively portray ...

Amazon deforestation up 29 pc in 2013

4 hours ago

Deforestation in the Amazon rose 29 percent between August 2012 and July of last year to 5,891 square kilometers (2,275 square miles), Brazilian officials said Wednesday, posting an amended figure.

Recommended for you

For electronics beyond silicon, a new contender emerges

12 hours ago

Silicon has few serious competitors as the material of choice in the electronics industry. Yet transistors, the switchable valves that control the flow of electrons in a circuit, cannot simply keep shrinking ...

Making quantum dots glow brighter

14 hours ago

Researchers from the University of Alabama in Huntsville and the University of Oklahoma have found a new way to control the properties of quantum dots, those tiny chunks of semiconductor material that glow ...

The future face of molecular electronics

15 hours ago

The emerging field of molecular electronics could take our definition of portable to the next level, enabling the construction of tiny circuits from molecular components. In these highly efficient devices, ...

Study sheds new light on why batteries go bad

Sep 14, 2014

A comprehensive look at how tiny particles in a lithium ion battery electrode behave shows that rapid-charging the battery and using it to do high-power, rapidly draining work may not be as damaging as researchers ...

Moving silicon atoms in graphene with atomic precision

Sep 12, 2014

Richard Feynman famously posed the question in 1959: is it possible to see and manipulate individual atoms in materials? For a time his vision seemed more science fiction than science, but starting with groundbreaking ...

User comments : 0