Improve efficiency and long lifetime UVC LEDs with wavelengths between 230 and 237 nm

Abstract

We demonstrate high output power UVC-LEDs from 230 to 237 nm on AlN single-crystal substrates. The UVC-LEDs show a single peak in the electroluminescence spectrum, from 20 to 300 mA. Forward voltages were typically ∼7 V at 100 mA while measured initial output powers at 237 nm, 235 nm, 233 nm and 230 nm were 2.2 mW, 1.9 mW, 1.5 mW and 1.2 mW, respectively. At 20 mA, the measured wall-plug efficiencies were 0.37%, 0.32%, 0.25% and 0.19% at the same wavelengths, respectively. These devices have demonstrated over 3600 h of lifetime operating at 20 mA.

Skin tolerant inactivation of multiresistant pathogens using far-UVC LEDs

“…The same applies to the application of lasers 23 . Only recently, LEDs with a peak emission wavelength in the range of 230–240 nm and milliwatt output powers have been demonstrated for the first time 24 , 25 after detailed optimization of the design and manufacturing conditions 26 – 29 . In the long run, far-UVC LEDs should be superior to excimer lamps in many ways.…”

Miniature plasma source for in situ extreme ultraviolet lithographic scanner cleaning

“…This works by temporarily offering additional free electrons until the feedback mechanism of electron emission by accelerated ions incident upon the cathode is sufficiently established [14]. Besides a second plasma, ignition at lower pressure can be enhanced by several means, such as (i) changing window material to quartz instead of sapphire (improving in-coupling of power by lower permittivity of the window material), (ii) adding magnets to create helical trajectories for the electrons, thereby increasing the effective electron path length in the gas [15], (iii) matching the driving frequency to the electron collision frequency [13], (iv) photoelectric electron emission by UV-LED [16,17]. Other options such as piezo-induced spark or thermionic emission from a sharp needle are possible in theory, but are not considered due to concerns over particle generation.…”

UV-Based Technologies for SARS-CoV2 Inactivation: Status and Perspectives

“…At the time being, their lifetime is not comparable with the one of the visible counterparts, but in recent years there was a marked improvement that bring some UVB LEDs to reach lifetime of over 10,000 h (data provided by UV LED manufacturer on device datasheet). On the other hand, UVC LEDs has not demonstrated yet this long lifetime, stopping at a value of about few hundred or thousand hours [60,61].…”