Highly efficient and reliable high power InGaN/GaN LEDs with 3D patterned step‐like ITO and wavy sidewalls

Abstract

Nitride‐based high power LEDs with finger‐like SiO2 current blocking layer (CBL), three‐dimensional (3D) patterned step‐like ITO double layers and wavy sidewalls were fabricated. The finger‐like SiO2 CBL beneath finger‐like p‐electrode was designed to prevent current crowding effect, thereby facilitating uniform current spreading over the entire chip. In addition, 3D patterned step‐like ITO double layers, including alternating 230 nm thick patterned upper step ITO layer and 100 nm thick lower step ITO layer, were formed by combining photolithography and aqua regia etchant. We showed that the top light extraction efficiency of high power LEDs can be significantly enhanced by taking 3D patterned step‐like ITO. The light output power of high power LEDs with 3D patterned step‐like ITO double layers is 13.9% higher than that of LEDs with smooth ITO layer. High‐power LEDs with wavy sidewalls was fabricated by an optimized mask design in conjunction with dry etching process based on Cl2/BCl3 to improve light extraction efficiency at the horizontal direction. We demonstrated that light output power of high power LEDs with wavy sidewalls can be improved by 11% as compared to LEDs with flat sidewalls.