Picosun's ALD technology boosts UVC LED performance
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.
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.
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