Design and Fabrication of a TiO2/SiO2 Dielectric Broadband and Wide-Angle Reflector and Its Application to GaN-Based Blue LEDs

In this paper, optical software and ion-assisted e-gun evaporation with radio frequency neutralizer were applied to simulate and fabricate a broadband reflector, respectively. It can almost reach 100% between 400 and 630 nm and between 400 and 580 nm with light incident angles of 5° and 45°, respectively. With 350-mA current injection, it was found that we achieved 34% enhancement in the GaN-based blue LEDs output power by the formation of a broadband reflector. Furthermore, it can be seen clearly that the optical microscopes images of the LEDs with an 11 pairs distributed Bragg reflector and with a broadband reflector were brighter than that of the LED without a reflector. The LED with a broadband reflector is the brightest of all LEDs. This result agrees with that observed in the current-output power characteristics.