Effect of ring-shaped SiO2 current blocking layer thickness on the external quantum efficiency of high power light-emitting diodes. (1st December 2017)

• Record Type: Journal Article
• Authors: Zhou, Shengjun; Liu, Mengling; Hu, Hongpo; Gao, Yilin; Liu, Xingtong
• Is Part Of: Optics & laser technology. Volume 97(2017)
• Page Start: 137
• Page End: 143
• Publication Date: 2017-12-01
• Subjects: Optics -- Periodicals; Lasers -- Periodicals; Electronic journals; 621.366
• DOI: 10.1016/j.optlastec.2017.06.020
• Languages: English
• ISSNs: 0030-3992

Abstract

Highlights: A ring-shaped SiO2 current blocking layer was employed to enhance current spreading of light-emitting diodes. A 190-nm-thick ring-shaped SiO2 current blocking layer with inclined sidewall was formed. Effects of ring-shaped SiO2 current blocking layer thickness were investigated. Abstract: A ring-shaped SiO2 CBL underneath the p-electrode was employed to enhance current spreading of GaN-based light-emitting diodes (LEDs). Effects of ring-shaped SiO2 current blocking layer (CBL) thickness on optical and electrical characteristics of high power LEDs were investigated. A 190-nm-thick ring-shaped SiO2 CBL with inclined sidewalls was obtained using a combination of a thermally reflowed photoresist technique and an inductively coupled plasma (ICP) etching process, allowing for the deposition of conformal indium tin oxide (ITO) transparent conductive layer on sidewalls of ring-shaped SiO2 CBL. It was indicated that the external quantum efficiency (EQE) of high power LEDs increased with increasing thickness of ring-shaped SiO2 CBL. The EQE of high power LED with 190-nm-thick ring-shaped SiO2 CBL was 12.7% higher than that of high power LED without SiO2 CBL. Simulations performed with commercial SimuLED software package showed that the ring-shaped SiO2 CBL could significantly alleviate current crowding around p-electrode, resulting in enhanced current spreading over the entire high power LED structure.