Improved Light Extraction of GaN-based LED with Patterned Ga-doped ZnO Transparent Conducting Layer

In this study, patterned Ga-doped ZnO transparent conducting layers were made to increase the light-extraction efficiency of GaN-based LEDs. The patterns were designed by different side length, spacing and depth of the concave squares. Simulations and experiments were taken to study the light output powers of LEDs made by patterned transparent conducting layers. The area of the vertical sidewalls of the patterns is thought to have important effect on the light extraction of LEDs. With bigger sidewalls, the escape possibility of photon can be increased. Compared with conventional LEDs with planar Ga-doped ZnO transparent conducting layers, the light output power can be increased by 8.9% via using 10 mu m side length, 5 mu m spacing and 400 nm depth concave square patterns, which is basically consistent with the simulated results.