Enhanced performance of GaN-based visible flip-chip mini-LEDs with highly reflective full-angle distributed Bragg reflector

The GaN-based high-voltage flip chip light-emitting diode (HVFC-LED) is designed and developed for the purpose of efficiency enhancement. In our design, the distributed Bragg reflector (DBR) is deposited at the bonded substrate to increase the light extraction. After the flip chip process, the general current-voltage characteristics between the flip chip sample and the traditional sample are essentially the same. With the help of great thermal conductive silicon substrate and the bottom DBR, the HVFC-LED is able to enhance the power by 37.1% when compared to the traditional high-voltage LEDs. The wall-plug efficiencies of the HVFC-LED also show good droop reduction as high as 9.9% compared to the traditional devices.

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Improving the External Quantum Efficiency of High Power GaN Based Flip-Chip LEDs using Ag/SiO2/DBR/SiO2 Composite ReflectiveStructure

10.21203/rs.3.rs-204748/v1 ◽

2021 ◽

Author(s):

Liang Xu ◽

Jinglin Zhan ◽

Huiqing Sun ◽

Zhizhong Chen ◽

Zhiyou Guo

Keyword(s):

Quantum Efficiency ◽

High Power ◽

External Quantum Efficiency ◽

Flip Chip ◽

Light Emission ◽

Light Output ◽

Vertical Direction ◽

Bragg Reflector ◽

Light Extraction Efficiency ◽

Distributed Bragg Reflector

Abstract Improve the light extraction efficiency and light output in the vertical direction of LEDs for high-power applications, flip-chip LEDs (FCLEDs) with an Ag/SiO2/distributed Bragg reflector/SiO2 composite reflection structure (CRS) were fabricated. The enhanced opto-electrical properties were thoroughly investigated. Compared with the normal Ag-based FCLEDs, the light output power of the CRS-FCLEDs is increased by 6.3% at an operational current of 1500 mA, with the corresponding external quantum efficiency improved by 6.0%. Further investigation proved that the CRS structure exhibited higher reflectance compared with the commonly used Ag-mirror reflective structure, which originates from the increased reflective area in the sidewall and partial area of the n-GaN contact holes. Moreover, the light emission intensity distributions and far-field angular light emission measurements show that the CRS-FCLED has a strengthened light output in the vertical direction, which shows great potential for applications in high-power fields, such as headlamps for automobiles.

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High performance GaN flip-chip light-emitting diodes with TiO2/SiO2 distributed Bragg reflector

International Photonics and OptoElectronics ◽

10.1364/oedi.2015.jw3a.12 ◽

2015 ◽

Cited By ~ 1

Author(s):

Jin Xu ◽

Wei Zhang ◽

Jiangnan Dai ◽

Zhihao Wu ◽

Yanyan Fang ◽

...

Keyword(s):

High Performance ◽

Flip Chip ◽

Light Emitting Diodes ◽

Bragg Reflector ◽

Distributed Bragg Reflector ◽

Light Emitting

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Effect of Dielectric Distributed Bragg Reflector on Electrical and Optical Properties of GaN-Based Flip-Chip Light-Emitting Diodes

Micromachines ◽

10.3390/mi9120650 ◽

2018 ◽

Vol 9 (12) ◽

pp. 650 ◽

Cited By ~ 6

Author(s):

Shengjun Zhou ◽

Haohao Xu ◽

Mengling Liu ◽

Xingtong Liu ◽

Jie Zhao ◽

...

Keyword(s):

Flip Chip ◽

Heat Dissipation ◽

High Efficiency ◽

Light Emitting Diodes ◽

Incident Angle ◽

Light Output ◽

Bragg Reflector ◽

Distributed Bragg Reflector ◽

Light Emitting ◽

Via Hole

We demonstrated two types of GaN-based flip-chip light-emitting diodes (FCLEDs) with distributed Bragg reflector (DBR) and without DBR to investigate the effect of dielectric TiO2/SiO2 DBR on optical and electrical characteristics of FCLEDs. The reflector consisting of two single TiO2/SiO2 DBR stacks optimized for different central wavelengths demonstrates a broader reflectance bandwidth and a less dependence of reflectance on the incident angle of light. As a result, the light output power (LOP) of FCLED with DBR shows 25.3% higher than that of FCLED without DBR at 150 mA. However, due to the better heat dissipation of FCLED without DBR, it was found that the light output saturation current shifted from 268 A/cm2 for FCLED with DBR to 296 A/cm2 for FCLED without DBR. We found that the use of via-hole-based n-type contacts can spread injection current uniformly over the entire active emitting region. Our study paves the way for application of DBR and via-hole-based n-type contact in high-efficiency FCLEDs.

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