Light Guide Layer Thickness Optimization for Enhancement of the Light Extraction Efficiency of Ultraviolet Light–Emitting Diodes

Nanoscale Research Letters

Yuan-Heng Cheng¹  Zhi Ting Ye¹  Li-Wei Hung²  Kung-Hsieh Hsu²  Yu Chang Hu³ 

[1] Department of Mechanical Engineering, Advanced Institute of Manufacturing With High-Tech Innovations, National Chung Cheng University, 168, University Rd., Min-Hsiung, 62102, Chia-Yi, Taiwan;Department of Process Development Division, EPILEDS TECHNOLOGIES, No. 7, Kanxi Rd., Xinshi Dist., 744092, Tainan City, Taiwan;Department of R&D Division, Harvatek Corporation, No. 18, Ln. 522, Sec. 5, Zhonghua Rd., Xiangshan Dist., 300066, Hsinchu City, Taiwan;

关键词: Deep-ultraviolet light-emitting diodes;    Light extraction efficiency;    Light guide layer;    First-order optical design;   

DOI  :  10.1186/s11671-021-03563-6

来源: Springer

【 摘 要 】

Consider material machinability and lattice mismatch sapphire as substrates for the ultraviolet-C light-emitting diodes (UV-C LEDs) are commonly used, but their high refractive index can result in the total internal reflection (TIR) of light whereby some light is absorbed, therefore caused reducing light extraction efficiency (LEE). In this study, we propose a method to optimize the thickness of a sapphire substrate light guide layer through first-order optical design which used the optical simulation software Ansys SPEOS to simulate and evaluate the light extraction efficiency. AlGaN UV-C LEDs wafers with a light guide layer thickness of 150–700 μm were used. The simulation proceeded under a center wavelength of 275 nm to determine the optimal thickness design of the light guide layer. Finally, the experimental results demonstrated that the initial light guide layer thickness of 150 μm the reference output power of 13.53 mW, and an increased thickness of 600 um resulted in output power of 20.58 mW. The LEE can be increased by 1.52 times through light guide layer thickness optimization. We propose a method to optimize the thickness of a sapphire substrate light guide layer through first-order optical design. AlGaN UV-C LEDs wafers with a light guide layer thickness of 150–700 μm were used. Finally, the experimental results demonstrated that the LEE can be increased by 1.52 times through light guide layer thickness optimization.

【 授权许可】

CC BY