Improvement in light output intensity of InGaN/GaN multiple-quantum-well blue light-emitting diode by SiO2/Si3N4 distributed Bragg reflectors and silver back mirror

In this article, the light output intensity of InGaN/GaN multiple-quantum-well (MQW) light emitting diodes (LEDs) is improved by using SiO2/Si3N4 distributed Bragg reflectors (DBRs) as window layer and Ag back mirror. The SiO2/Si3N4 DBRs can take several advantages, such as high reflectance with less number of DBR, passive characteristics, and high reliability due to growth in one pump down growth system. The experimental results indicated that InGaN/GaN LEDs with the 3-pair of SiO2/Si3N4 DBRs show a maximum light output intensity of 64 mcd under 20 mA driving current and an improvement of 42% as compared to that of InGaN/GaN LEDs without SiO2/Si3N4 DBRs. In addition, the turn-on voltage, forward resistance, and full width at half maximum (FWHM) of the emission spectra for InGaN/GaN LEDs with the 3-pair of SiO2/Si3N4 DBRs and Ag back mirror are 3.23 V, 16 Ω, and 22.4 nm under 20 mA forward current.