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

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.