Surface Texturing of High-Power Flip-Chip LEDs by Femtosecond Laser Direct Structuring

We report on the femtosecond laser direct structuring of the sapphire flipside surfaces of high-power flip-chip LEDs. It is found that diameter and depth of the created submicrometer-sized holes can be manipulated by varying the laser power at a constant number of laser pulses. This method enables the control of the structure sizes with high precision. Our study shows that the light extraction from such LEDs increases strongly with increasing hole sizes.