Title :
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
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;
Journal_Title :
Photonics Technology Letters, IEEE
DOI :
10.1109/LPT.2013.2275969
