The market for UV-C disinfection is blossoming, driven partly by recent outbreaks and fear of viruses and bacteria such as SARS, MERS, MRSA, Ebola, norovirus and C-DIFF. UV LEDs can play a useful role in preventing infectious disease. They may be used to make water potable, replace chlorine as a water disinfectant in swimming pools, kill germs in clothes washers and dishwashers, kill airborne germs in air purifiers and HVAC systems, and disinfect surfaces in hospitals, kitchens, schools, offices and nursing homes. UV-C LED products are already available for high-end applications like industrial water purification, but there is a strong push to reduce the cost of the LED chips in order to address the very large consumer market for disinfection.
A challenge in packaging UV-C LEDs is the window mounted atop the LED package. Nearly all organic materials absorb UV-C radiation, so the same “glob top” silicones used atop visible light, UV-A and UV-B LEDs are inappropriate for UV-C LEDs. The only two practical window materials for UV-C LEDs are high purity silica glass (fused silica SiO2) and sapphire (Al2O3). Another unique challenge with UV-C LEDs is their low efficiency; conventional UV-C LEDs have an efficiency ≤ 15%, so it is very important to include an anti-reflective (AR) coating on both faces of the window in order to maximize photon emission from the package.