- In order to reach maximum light output and long operating lifetime,
LED chips require surface passivation to eliminate parasitic currents
caused by traps and defects
- ALD
passivation layer could potentially replace the expensive hermetic seal
package of the LEDs and thus lower the costs of the final device.
- Short-wavelength UVC radiation destroys bacteria and viruses so UVC
LED technology is particularly topical now during the still ongoing
COVID-19 pandemic.
ESPOO, Finland, 24th September 2020 – Picosun Group, the leading supplier of AGILE ALD®
(Atomic Layer Deposition) thin film coating technology, reports
excellent results in UVC (ultraviolet-C) LED performance, achieved with
the company’s ALD solutions.
Excellent reliability and lifetime improvements of UVC LEDs have been
obtained at Picosun’s customer and collaboration partner site, National
Chiao Tung University (NCTU), Taiwan, using passivation and barrier
films deposited with PICOSUN® ALD equipment(*). ALD
passivation layer could potentially replace the expensive hermetic seal
package of the LEDs and thus lower the costs of the final device.
“We have used Picosun’s ALD technology already for years with great success. Our PICOSUN®
ALD equipment yields superior quality films which has helped us to
achieve several breakthroughs in our LED research. Picosun has local
presence in Taiwan and we appreciate the prompt response of their
customer support if we ever have any issues. At the phase when R&D
results are to be ramped up to industrial-level production, the
scalability of Picosun’s ALD technology is a huge benefit,” comments
Professor Hao-Chung Kuo from NCTU.
In order to reach maximum light output and long operating lifetime,
LED chips require surface passivation to eliminate parasitic currents
caused by traps and defects. Also barrier coating is typically needed as
LED materials are sensitive to moisture. ALD is an ideal technique to
manufacture both the passivation and barrier films – and when the LED
size diminishes to micrometer dimensions, the only coating method
capable of producing high enough quality films on the required minuscule
scale. Ultra-thin, pinhole-free ALD films do not suppress the LED light
intensity and they provide reliable protection against ambient
conditions, whereas their superior conformality ensures no thickness
variations between the facets of the LED chip. Thickness variations,
typical side effect of other coating methods, can potentially lead to
uneven distribution of film stress or thermal expansion behavior and
risk physical damage of the chip.
Short-wavelength UVC radiation destroys bacteria and viruses so UVC
LED technology is particularly topical now during the still ongoing
COVID-19 pandemic. Small, lightweight LEDs enable versatile design of
portable, compact disinfecting equipment, they consume less power than
other UVC sources, they are durable, and they pose no risk of hazardous
material leaks such as e.g. mercury lamps.
“We are happy of the achievements of Professor Kuo’s group at NCTU,
and how Picosun’s ALD technology has helped them to achieve their goals
in UVC LED development. Our long-term collaboration and networking with
both the academia and prominent industries in this field gives us the
perfect synergy advantage to facilitate implementation of these
solutions in industrial manufacturing,” says Mr. Edwin Wu, CEO of
Picosun Asia Pte. Ltd.
(*) UVC LED with 50 nm ALD Al2O3 passivation
and normal LED packaging (no hermetic seal) maintained 80% of its
original efficiency even after 500 hours environmental test at 85%
humidity and 85 oC temperature.