Light Extraction Enhancement of Vertical LED by Growing ZnO Nano-Rods on Tips of Pyramids

Author

Yen-Ju Wu ; Yen-Shuo Liu ; Chih-Yi Hsieh ; Po-Ming Lee ; Yu-Shan Wei ; You-Hsien Chang ; Kun-Yu Lai ; Cheng-Yi Liu

Author_Institution

Chem. & Mater. Eng. Dept., Nat. Central Univ., Jhongli, Taiwan

Volume

25

Issue

18

fYear

2013

fDate

Sept.15, 2013

Firstpage

1774

Lastpage

1777

Abstract

Creating a pyramidal structure on an n-GaN surface is considered the most effective approach for maximizing light extraction of n-side-up GaN-based light-emitting diodes (LEDs). This letter shows that the light extraction efficiency of a pyramidal n-GaN surface can be further enhanced by growing ZnO nano-rods (NRs) specifically on the tips of the pyramids on the n-GaN surface. Using tip-only ZnO NRs, the light-output power of an n-side-up LED with a pyramidal n-GaN surface can be further enhanced by 49.6% at 250 mA. This improved light extraction efficiency is due to the multiple facets on the ZnO NRs.

Keywords

II-VI semiconductors; III-V semiconductors; gallium compounds; light emitting diodes; nanophotonics; nanorods; wide band gap semiconductors; zinc compounds; GaN; ZnO-GaN; current 250 mA; light extraction enhancement; light-output power; n-side-up GaN-based light-emitting diodes; nanorods; pyramidal n-GaN surface; pyramidal structure; tip-only ZnO NR; vertical LED; Gallium nitride; Light emitting diodes; Surface impedance; Surface morphology; Surface treatment; Zinc oxide; Hydrothermal; ZnO; nano-rods; nanotechnology; surface roughening;

fLanguage

English

Journal_Title

Photonics Technology Letters, IEEE

Publisher

ieee

ISSN

1041-1135

Type

jour

DOI

10.1109/LPT.2013.2275969

Filename

6573355