Created a far-ultraviolet diode that works at room temperature

Researchers from Nagoya University led by Nobel Prize laureate in physics Hiroshi Amano

successfully conducted the world's first continuousgeneration of deep ultraviolet radiation at room temperature using a laser diode. The device developed by scientists produces waves with a frequency of less than 280 nm (far ultraviolet, UV-C).

Demonstration of the first continuous wave far-ultraviolet diode. Video: Nagoya University's Institute of Materials and Systems for Sustainability

Back in 2019, the research team createda short wavelength ultraviolet-visible (UV-C) laser diode that operates with short current pulses. However, the input power required to generate these pulses was 5.2 watts. This was too much for continuous generation, since the power caused the diode to quickly heat up and stop working.

In a new paper published in the journal AppliedPhysics Letters, physicists redesigned the device, reducing the drive power needed to operate the laser to just 1.1 watts at room temperature. The scientists found that previously created devices required high power due to crystal defects occurring on the laser stripe.

Scheme of the design and development of laser diodes. Image: Issey Takahashi, Nagoya University's Institute of Materials and Systems for Sustainability

Further analysis showed that these defectsoccur due to deformation of the crystal. By choosing the correct side walls of the laser strip, the scientists suppressed the defects, achieving efficient current flow into the active region of the laser diode and reducing the operating power.

Laser diodes have found wide application in the mostdifferent areas. For example, infrared radiation is used in optical radiation devices, and blue radiation is used in Blu-Ray discs. The authors of the development believe that the new technology for creating UV-C radiation will be useful in healthcare, virus detection, particulate matter measurement, gas analysis and high-resolution laser processing.

Especially researchers note the prospects for using new diodes for air sterilization and water purification.

Unlike current LED sterilization methods, which require a large amount of time, lasers can disinfect large areas in a short time and over long distances.

Zhang Ziyi, study co-author

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On the cover: a source of continuous ultraviolet radiation. Image: Asahi Kasei Corp. and Nagoya University