Nanotube photodetector built

February 27, 2013
This illustration shows an array of parallel carbon nanotubes 300 micrometers long that are attached to electrodes and display unique qualities as a photodetector, according to researchers at Rice University and Sandia National Laboratories. Credit: Sandia National Laboratories

Researchers at Rice University and Sandia National Laboratories have made a nanotube-based photodetector that gathers light in and beyond visible wavelengths. It promises to make possible a unique set of optoelectronic devices, solar cells and perhaps even specialized cameras.

A traditional camera is a light detector that captures a record, in chemicals, of what it sees. Modern digital cameras replaced film with semiconductor-based detectors.

But the Rice detector, the focus of a paper that appeared today in the online Scientific Reports, is based on extra-long carbon nanotubes. At 300 micrometers, the nanotubes are still only about 100th of an inch long, but each tube is thousands of times longer than it is wide.

That boots the broadband detector into what Rice physicist Junichiro Kono considers a macroscopic device, easily attached to for testing. The nanotubes are grown as a very thin "carpet" by the lab of Rice chemist Robert Hauge and pressed horizontally to turn them into a of hundreds of thousands of well-aligned tubes.

They're all the same length, Kono said, but the nanotubes have different widths and are a mix of conductors and semiconductors, each of which is sensitive to different wavelengths of light. "Earlier devices were either a single nanotube, which are sensitive to only limited wavelengths," he said. "Or they were random networks of nanotubes that worked, but it was very difficult to understand why."

"Our device combines the two techniques," said Sébastien Nanot, a former in Kono's group and first author of the paper. "It's simple in the sense that each nanotube is connected to both electrodes, like in the single-nanotube experiments. But we have many nanotubes, which gives us the quality of a macroscopic device."

With so many nanotubes of so many types, the array can detect light from the infrared (IR) to the ultraviolet, and all the in between. That it can absorb light across the spectrum should make the detector of great interest for solar energy, and its IR capabilities may make it suitable for military imaging applications, Kono said. "In the visible range, there are many good detectors already," he said. "But in the IR, only low-temperature detectors exist and they are not convenient for military purposes. Our detector works at room temperature and doesn't need to operate in a special vacuum."

The detector is also sensitive to polarized light and absorbs light that hits it parallel to the nanotubes, but not if the device is turned 90 degrees.

The work is the first successful outcome of a collaboration between Rice and Sandia under Sandia's National Institute for Nano Engineering program funded by the Department of Energy. François Léonard's group at Sandia developed a novel theoretical model that correctly and quantitatively explained all characteristics of the nanotube . "Understanding the fundamental principles that govern these photodetectors is important to optimize their design and performance," Léonard said.

Kono expects many more papers to spring from the collaboration. The initial device, according to Léonard, merely demonstrates the potential for nanotube photodetectors. They plan to build new configurations that extend their range to the terahertz and to test their abilities as imaging devices. "There is potential here to make real and useful devices from this fundamental research," Kono said.

Explore further: Nanotube-based terahertz polarizer nears perfection

More information: … /full/srep01335.html

Related Stories

Nanotube-based terahertz polarizer nears perfection

January 30, 2012

( -- Researchers at Rice University are using carbon nanotubes as the critical component of a robust terahertz polarizer that could accelerate the development of new security and communication devices, sensors ...

Sandia researcher examines the physics of carbon nanotubes

May 1, 2008

Carbon nanotubes, described as the reigning celebrity of the advanced materials world, are all the rage. Recently researchers at Rice University and Rensselaer Polytechnic Institute used them to make the “blackest black” ...

Carbon nanotube device can detect colors of the rainbow

April 30, 2009

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, ...

Recommended for you

Quantum computing building blocks

July 24, 2017

For decades scientists have known that a quantum computer—a device that stores and manipulates information in quantum objects such as atoms or photons—could theoretically perform certain calculations far faster than today's ...

Here's a tip: Indented cement shows unique properties

July 19, 2017

Rice University scientists have determined that no matter how large or small a piece of tobermorite is, it will respond to loading forces in precisely the same way. But poking it with a sharp point will change its strength.

Nanoparticles could spur better LEDs, invisibility cloaks

July 19, 2017

In an advance that could boost the efficiency of LED lighting by 50 percent and even pave the way for invisibility cloaking devices, a team of University of Michigan researchers has developed a new technique that peppers ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Mar 02, 2013
Efficiency? Quantum dots, nanotubes and metal solar cells?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.