Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Thermal vision: Graphene light detector first to span infrared spectrum

17.03.2014

The first room-temperature light detector that can sense the full infrared spectrum has the potential to put heat vision technology into a contact lens.

Unlike comparable mid- and far-infrared detectors currently on the market, the detector developed by University of Michigan engineering researchers doesn't need bulky cooling equipment to work.

"We can make the entire design super-thin," said Zhaohui Zhong, assistant professor of electrical engineering and computer science. "It can be stacked on a contact lens or integrated with a cell phone."

Infrared light starts at wavelengths just longer than those of visible red light and stretches to wavelengths up to a millimeter long. Infrared vision may be best known for spotting people and animals in the dark and heat leaks in houses, but it can also help doctors monitor blood flow, identify chemicals in the environment and allow art historians to see Paul Gauguin's sketches under layers of paint.

Unlike the visible spectrum, which conventional cameras capture with a single chip, infrared imaging requires a combination of technologies to see near-, mid- and far-infrared radiation all at once. Still more challenging, the mid-infrared and far-infrared sensors typically need to be at very cold temperatures.

Graphene, a single layer of carbon atoms, could sense the whole infrared spectrum—plus visible and ultraviolet light. But until now, it hasn't been viable for infrared detection because it can't capture enough light to generate a detectable electrical signal. With one-atom thickness, it only absorbs about 2.3 percent of the light that hits it. If the light can't produce an electrical signal, graphene can't be used as a sensor.

"The challenge for the current generation of graphene-based detectors is that their sensitivity is typically very poor," Zhong said. "It's a hundred to a thousand times lower than what a commercial device would require."

To overcome that hurdle, Zhong and Ted Norris, the Gerard A. Mourou Professor of Electrical Engineering and Computer Science, worked with graduate students to design a new way of generating the electrical signal. Rather than trying to directly measure the electrons that are freed when light hits the graphene, they amplified the signal by looking instead at how the light-induced electrical charges in the graphene affect a nearby current.

"Our work pioneered a new way to detect light," Zhong said. "We envision that people will be able to adopt this same mechanism in other material and device platforms."

To make the device, they put an insulating barrier layer between two graphene sheets. The bottom layer had a current running through it. When light hit the top layer, it freed electrons, creating positively charged holes. Then, the electrons used a quantum mechanical trick to slip through the barrier and into the bottom layer of graphene.

The positively charged holes, left behind in the top layer, produced an electric field that affected the flow of electricity through the bottom layer. By measuring the change in current, the team could deduce the brightness of the light hitting the graphene. The new approach allowed the sensitivity of a room-temperature graphene device to compete with that of cooled mid-infrared detectors for the first time.

The device is already smaller than a pinky nail and is easily scaled down. Zhong suggests arrays of them as infrared cameras.

"If we integrate it with a contact lens or other wearable electronics, it expands your vision," Zhong said. "It provides you another way of interacting with your environment."

While full-spectrum infrared detection is likely to find application in military and scientific technologies, the question for the general tech market may soon be, "Do we want to see in infrared?"

The device is described in a paper titled "Graphene photodetectors with ultra-broadband and high responsivity at room temperature," which appears online in Nature Nanotechnology.

###

This work was supported by the National Science Foundation in part through Michigan Engineering's Center for Photonic and Multiscale Nanomaterials, and was carried out with help from electrical engineering and computer science doctoral students Chang-Hua Liu and You-Chia Chang.

Zhaohui Zhong: http://www.eecs.umich.edu/zhonglab

Center for Photonic and Multiscale Nanomaterials: http://cphom.engin.umich.edu

Kate McAlpine | EurekAlert!

Further reports about: Photonic Thermal cameras detector electrons graphene lens sensitivity spectrum technologies wavelengths

More articles from Physics and Astronomy:

nachricht When helium behaves like a black hole
22.03.2017 | University of Vermont

nachricht Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars
22.03.2017 | International Centre for Radio Astronomy Research

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Pulverizing electronic waste is green, clean -- and cold

22.03.2017 | Materials Sciences

Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars

22.03.2017 | Physics and Astronomy

New gel-like coating beefs up the performance of lithium-sulfur batteries

22.03.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>