Improved Extraction Efficiency of Light-Emitting Diodes by Wet-Etching Modifying AZO Surface Roughness

Author

Kuo, Ting-Wei ; Lin, Shi-Xiong ; Hung, Yueh-Yu ; Horng, Jui-Hong ; Houng, Mau-Phon

Author_Institution

Dept. of Electr. Eng., Nat. Cheng-Kung Univ., Tainan, Taiwan

Volume

23

Issue

6

fYear

2011

fDate

3/15/2011 12:00:00 AM

Firstpage

362

Lastpage

364

Abstract

In this letter, the AlGaInP light-emitting diodes (LEDs) between the air and GaP layer are added to the textured ZnO:Al (AZO) films in order to improve light extraction of the device. At 20 mA, the relative luminous intensity of textured AZO LEDs is increased by 129.9% when compared with the conventional sample. Furthermore, the far-field radiation pattern was improved with intensity not only at 0^° , but also from 60° to 300° . Due to loss of internal Fresnel efficiency and critical angle efficiency, textured AZO LEDs are significantly improved by the wet-etching technique. The surface treatment of AZO films generates surface texturing that is characterized as random crater. It presents a better far-field radiation pattern when compared with nontextured AZO films. This letter has demonstrated the far-field radiation pattern and the theory for enhancing light emission efficiency of LEDs.

Keywords

II-VI semiconductors; III-V semiconductors; aluminium; aluminium compounds; etching; gallium compounds; light emitting diodes; surface roughness; zinc compounds; AlGaInP; LED; ZnO:Al; critical angle efficiency; current 20 mA; extraction efficiency; far field radiation pattern; internal Fresnel efficiency; light emitting diode; wet etching modifying surface roughness; AZO; ZnO; ZnO:Al; crater; light-emitting diodes (LEDs); surface modify; surface roughness; wet-etching;

fLanguage

English

Journal_Title

Photonics Technology Letters, IEEE

Publisher

ieee

ISSN

1041-1135

Type

jour

DOI

10.1109/LPT.2011.2105863

Filename

5686915