Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A better device to detect ultraviolet light

07.10.2013
New type of photodiode, described in the journal Applied Physics Letters, shows promise for space-based communication and monitoring ozone depletion

Researchers in Japan have developed a new photodiode that can detect in just milliseconds a certain type of high-energy ultraviolet light, called UVC, which is powerful enough to break the bonds of DNA and harm living creatures. The researchers describe their new device in the journal Applied Physics Letters.



This is a crystal model of beta-Ga2O3.
Credit: Ishinomaki/S.Nakagomi

Although this radiation doesn't normally reach the Earth's surface, it can leak through to just below the hole in the ozone layer. Monitoring this radiation is a way of tracking the hole in the ozone layer, and photodiodes that measure UVC are also used as flame sensors and for communication in space.

Now, Shinji Nakagomi and colleagues at Ishinomaki Senshu University in Japan have built a new kind of photodiode that can detect the whole range of UVC light while remaining insensitive to visible light from the sun -- two features that have eluded designers of current devices. By being "solar blind," photodiodes are more sensitive to the UVC range and are thus more useful.

Building a Better Photodiode

Some photo detectors consist of vacuum tubes on sale, but they have short lifetimes and are relatively large and unwieldy. Today, many photodiodes are instead based on a so-called p-n junction, in which a semiconductor that carries positive charge (the absence of electrons called holes) is put in contact with the same semiconductor that instead carries negative charge (electrons). When light with sufficient energy (short wavelength) strikes atoms near the interface between the two semiconductors -- called p-type and n-type, respectively -- it generates mobile electrons and holes, boosting electrical current across the p-n junction and signaling the presence of light.

Other photodiodes made from materials like aluminum nitride and diamond are sensitive only to a limited range of UVC light. But recently, gallium oxide has shown promise because it's sensitive to the entire UVC range and is solar blind. The problem, however, is that it's difficult to make p-type gallium oxide.

Instead of a photodiode based on a conventional p-n junction, the researchers built one based on what's called a heterojunction, which is a p-n junction that incorporates two different semiconductors. The team used gallium oxide and silicon carbide, and found that their device responds quickly to UV light -- within milliseconds -- and has little dark current, which is the intrinsic electrical current that flows through the device even in the absence of light. Minimal dark current is important for a sensitive photodiode.

"The most important aspect about our device is that it is based on a heterojunction between gallium oxide and silicon carbide," said Nakagomi. "This gallium oxide and silicon carbide photodiode is promising for the detection of UV light."

The paper, "Deep ultraviolet photodiodes based on â-Ga2O3/SiC Heterojunction" is authored by Shinji Nakagomi, Toshihiro Momo, Syuhei Takahashi, and Yoshihiro Kokubun and appears in the journal Applied Physics Letters. See: http://dx.doi.org/10.1063/1.4818620

ABOUT THE JOURNAL

Applied Physics Letters features concise, rapid reports on significant new findings in applied physics. The journal covers new experimental and theoretical research on applications of physics phenomena related to all branches of science, engineering, and modern technology. See: http://apl.aip.org

Jason Socrates Bardi | EurekAlert!
Further information:
http://www.aip.org

More articles from Physics and Astronomy:

nachricht From rocks in Colorado, evidence of a 'chaotic solar system'
23.02.2017 | University of Wisconsin-Madison

nachricht Prediction: More gas-giants will be found orbiting Sun-like stars
22.02.2017 | Carnegie Institution for Science

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: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>