Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Laser diode emits deep UV light

20.01.2020

Nagoya University scientists, in cooperation with Asahi Kasei Corporation, have succeeded in designing a laser diode that emits deep-ultraviolet light, according to research published in the journal Applied Physics Express.

"Our laser diode emits the world's shortest lasing wavelength, at 271.8 nanometers (nm), under pulsed [electric] current injection at room temperature," says Professor Chiaki Sasaoka of Nagoya University's Center for Integrated Research of Future Electronics.


Far field pattern of UV-C laser projected onto a fluorescent screen.

Credit: 2019 Asahi Kasei Corp. and Nagoya University


Cross-sectional structure of the UV-C semiconductor laser diode.

Credit: 2019 Asahi Kasei Corp. and Nagoya University

Previous efforts in the development of ultraviolet laser diodes had only managed to achieve emissions down to 336 nm, Sasaoka explains.

Laser diodes that emit short-wavelength ultraviolet light, which is called UV-C and is in the wavelength region of 200 to 280 nm, could be used for disinfection in healthcare, for treating skin conditions such as psoriasis, and for analysing gases and DNA.

The Nagoya University deep-ultraviolet laser diode overcomes several issues encountered by scientists in their work towards the development of these semiconducting devices.

The team used a high quality aluminium nitride (AlN) substrate as their base for building up the layers of the laser diode. This, they say, is necessary, since lower quality AlN contains a large amount of defects, which ultimately impact the efficiency of a laser diode's active layer in converting electrical into light energy.

In laser diodes, a 'p-type' and 'n-type' layer are separated by a 'quantum well'. When an electric current is passed through a laser diode, positively charged holes in the p-type layer and negatively charged electrons in the n-type layer flow towards the center to combine, releasing energy in the form of light particles called photons.

The researchers designed the quantum well so that it would emit deep UV light. The p- and n-type layers were made from aluminium gallium nitride (AlGaN). Cladding layers, also made from AlGaN, were placed on either side of the p- and n-type layers. The cladding below the n-type layer included silicon impurities, a process called doping. Doping is used as a technique to modify a material's properties.

The cladding above the p-type layer underwent distributed polarization doping, which dopes the layer without adding impurities. The aluminium content in the p-side cladding was designed so that it was highest at the bottom, decreasing towards the top. The researchers believe this aluminium gradient enhances the flow of positively charged holes. A top contact layer was finally added that was made from p-type AlGaN doped with magnesium.

The researchers found that the polarization doping of the p-side cladding layer meant that a pulsed electric current of "remarkably low operating voltage" of 13.8V was needed for the emission of "the shortest wavelength reported so far."

The team is now conducting advanced joint research with Asahi Kasei Corporation to achieve continuous room temperature deep-UV lasing for the development of UV-C semiconductor laser products.

###

The article, "A 271.8 nm deep-ultraviolet laser diode for room temperature operation," was published online in Applied Physics Express on October 30, 2019, at DOI: 10.7567/1882-0786/ab50e0.

For more information, contact:
Prof. Chiaki Sasaoka
Center for Integrated Research of Future Electronics, Institute of Materials Research and System for Sustainability, Nagoya University
Email: sasaoka@nagoya-u.jp

About Nagoya University

Nagoya University has a history of about 150 years, with its roots in a temporary medical school and hospital established in 1871, and was formally instituted as the last Imperial University of Japan in 1939. Although modest in size compared to the largest universities in Japan, Nagoya University has been pursuing excellence since its founding. Six of the 18 Japanese Nobel Prize-winners since 2000 did all or part of their Nobel Prize-winning work at Nagoya University: four in Physics - Toshihide Maskawa and Makoto Kobayashi in 2008, and Isamu Akasaki and Hiroshi Amano in 2014; and two in Chemistry - Ryoji Noyori in 2001 and Osamu Shimomura in 2008. In mathematics, Shigefumi Mori did his Fields Medal-winning work at the University. A number of other important discoveries have also been made at the University, including the Okazaki DNA Fragments by Reiji and Tsuneko Okazaki in the 1960s; and depletion forces by Sho Asakura and Fumio Oosawa in 1954.

Chiaki Sasaoka | EurekAlert!
Further information:
http://en.nagoya-u.ac.jp/research/activities/news/2020/01/laser-diode-emits-deep-uv-light.html
http://dx.doi.org/10.7567/1882-0786/ab50e0

Further reports about: DNA Electronics Laser UV light UV-C diodes ultraviolet ultraviolet light wavelength

More articles from Physics and Astronomy:

nachricht Time-resolved measurement in a memory device
19.02.2020 | ETH Zurich

nachricht Studying electrons, bridging two realms of physics: connecting solids and soft matter
18.02.2020 | Tokyo University of 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: A step towards controlling spin-dependent petahertz electronics by material defects

The operational speed of semiconductors in various electronic and optoelectronic devices is limited to several gigahertz (a billion oscillations per second). This constrains the upper limit of the operational speed of computing. Now researchers from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, and the Indian Institute of Technology in Bombay have explained how these processes can be sped up through the use of light waves and defected solid materials.

Light waves perform several hundred trillion oscillations per second. Hence, it is natural to envision employing light oscillations to drive the electronic...

Im Focus: Freiburg researcher investigate the origins of surface texture

Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.

Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...

Im Focus: Skyrmions like it hot: Spin structures are controllable even at high temperatures

Investigation of the temperature dependence of the skyrmion Hall effect reveals further insights into possible new data storage devices

The joint research project of Johannes Gutenberg University Mainz (JGU) and the Massachusetts Institute of Technology (MIT) that had previously demonstrated...

Im Focus: Making the internet more energy efficient through systemic optimization

Researchers at Chalmers University of Technology, Sweden, recently completed a 5-year research project looking at how to make fibre optic communications systems more energy efficient. Among their proposals are smart, error-correcting data chip circuits, which they refined to be 10 times less energy consumptive. The project has yielded several scientific articles, in publications including Nature Communications.

Streaming films and music, scrolling through social media, and using cloud-based storage services are everyday activities now.

Im Focus: New synthesis methods enhance 3D chemical space for drug discovery

After helping develop a new approach for organic synthesis -- carbon-hydrogen functionalization -- scientists at Emory University are now showing how this approach may apply to drug discovery. Nature Catalysis published their most recent work -- a streamlined process for making a three-dimensional scaffold of keen interest to the pharmaceutical industry.

"Our tools open up whole new chemical space for potential drug targets," says Huw Davies, Emory professor of organic chemistry and senior author of the paper.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

70th Lindau Nobel Laureate Meeting: Around 70 Laureates set to meet with young scientists from approx. 100 countries

12.02.2020 | Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

 
Latest News

A step towards controlling spin-dependent petahertz electronics by material defects

19.02.2020 | Power and Electrical Engineering

Time-resolved measurement in a memory device

19.02.2020 | Physics and Astronomy

Mixed-signal hardware security thwarts powerful electromagnetic attacks

19.02.2020 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>