Study the Application of DBR in GaN LEDs

• Main Authors: Y.C.Lin, 林裕承
• Other Authors: H.P.Shiao
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/03279556080677983046

碩士 === 大葉大學 === 電機工程學系 === 98 === Due to the mature of epitaxy and process technologies, the application of nitride-based LEDs becomes more extensive. In order to improve the junction temperature and reduce the shading effect of electrodes, the flip-chip technology for LED package was also proposed and developed. The light will emit from substrate side surface for flip-chip packaged LEDs. The output intensity can be further enhanced if a reflector is deposited on the top surface of LEDs. In this thesis we have deposited a distributed Bragg reflector (DBR) on the top surface of LEDs to improve the output light intensity. The DBR is composed of SiO2 and TiO2. The reflectivity and transmittance were measured for the DBR samples with different pairs. From the measured results, a reflectivity of 91% at wavelength range of 450 ~ 470 nm was obtained from the DBR samples with 7.5 pairs. The light intensity emitted from top surface of the LED with DBR was reduced about 82%. Oppositely, the light intensity emitted from substrate side surface was enhanced about 30%.