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

Shengjun Zhou; Haohao Xu; Mengling Liu; Xingtong Liu; Jie Zhao; Ning Li; Sheng Liu

doi:10.3390/mi9120650

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

Micromachines (Basel). 2018 Dec 8;9(12):650. doi: 10.3390/mi9120650.

Authors

Shengjun Zhou^{1

2

3

4}, Haohao Xu^{5

6}, Mengling Liu^{7

8}, Xingtong Liu^{9

10}, Jie Zhao^{11

12}, Ning Li^{13

14}, Sheng Liu^{15

16}

Affiliations

¹ Key Laboratory of Hydraulic Machinery Transients, Ministry of Education, Wuhan University, Wuhan 430072, China. [email protected].
² Center for Photonic and Semiconductor, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China. [email protected].
³ Research Center of Electronic Manufacturing and Packaging Integration, Institute of Technological Sciences, Wuhan University, Wuhan 430072, China. [email protected].
⁴ State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China. [email protected].
⁵ Key Laboratory of Hydraulic Machinery Transients, Ministry of Education, Wuhan University, Wuhan 430072, China. [email protected].
⁶ Center for Photonic and Semiconductor, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China. [email protected].
⁷ Key Laboratory of Hydraulic Machinery Transients, Ministry of Education, Wuhan University, Wuhan 430072, China. [email protected].
⁸ Center for Photonic and Semiconductor, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China. [email protected].
⁹ Key Laboratory of Hydraulic Machinery Transients, Ministry of Education, Wuhan University, Wuhan 430072, China. [email protected].
¹⁰ Center for Photonic and Semiconductor, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China. [email protected].
¹¹ Key Laboratory of Hydraulic Machinery Transients, Ministry of Education, Wuhan University, Wuhan 430072, China. [email protected].
¹² Center for Photonic and Semiconductor, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China. [email protected].
¹³ Key Laboratory of Hydraulic Machinery Transients, Ministry of Education, Wuhan University, Wuhan 430072, China. [email protected].
¹⁴ Center for Photonic and Semiconductor, School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China. [email protected].
¹⁵ Key Laboratory of Hydraulic Machinery Transients, Ministry of Education, Wuhan University, Wuhan 430072, China. [email protected].
¹⁶ Research Center of Electronic Manufacturing and Packaging Integration, Institute of Technological Sciences, Wuhan University, Wuhan 430072, China. [email protected].

Abstract

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.

Keywords: distributed Bragg reflector; external quantum efficiency; flip-chip light-emitting diodes; light output power.

Abstract

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