The Efficiency and Reliability Improvement by Utilizing Quartz Airtight Packaging of UVC LEDs

This paper investigates a novel packaging that can effectively improve the efficiency and reliability of 280-nm deep ultraviolet (DUV) light-emitting diodes (LEDs). The experimental results showed that use of a quartz airtight package dramatically improves light extraction efficiency compared with conventional silicone encapsulant under a rated current of 20 mA. The transmittance of silicone decreases significantly as the wavelength below 300 nm. By enabling high transparency over a wide range of wavelengths in the DUV region, the quartz airtight package improved the light extraction efficiency of ultraviolet C LEDs. Thermal resistances of LEDs measured for two package types showed that junction temperatures were almost the same under the same driving current. In addition, the maintenance of radiative power when using the quartz airtight package was 13% higher than that when using the silicone package after 500 h aging test under 20 mA and 25°C. The silicone package LEDs exhibited significant intensity decay with aging time. The experimental results showed that the quartz airtight package is a reliable design that can effectively improve both efficiency and long-term reliability of DUV LEDs.