Enhanced Light Output of GaN-Based LEDs with Surface Structures using SU-8 Microlens and HTG ZnO Flim

• Main Authors: Ru-WenWu, 吳如雯
• Other Authors: Shui-Jinn Wang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/26468672913592479481

碩士 === 國立成功大學 === 微電子工程研究所 === 102 === This thesis aims at the development of a surface roughness technique through using SU-8 photoresist microlens and an HTG ZnO film to improve the light output power (Lop) of GaN light-emitting diodes (LEDs). This thesis is divided into two parts. The first part focuses on opitical simulation and experimental study. TracePro was used to simulate the size effects of the SU-8 microlens on the light output efficiency of LEDs, which indicates that SU-8 microlens with 8 m in diameter for the cylinder portion could be the optimum design. Experiments have been conducted using photolithography process to form SU-8 microlens arrays on the surface of conventional GaN-based LEDs. Experimental results show an improvement in Lop of LEDs with 8 m Cylinder diameter microlens structure by 14.1% at 350 mA, as compared with that of the regular LEDs. The second part of this thesis is devoted to clarify the growth mechanism of ZnO thin film on GaN epilayer, material analysis and its application on LEDs for light output enhancement. Hydrothermal growth (HTG) method was employed to grow ZnO thin film on p-GaN and n-GaN surface. Effects of the growth time and temperature on the film structure and quality were examined. Material analysis using SEM, XRD, TEM and EDS were made and single crystallinity of the grown ZnO films was confirmed.