以有限時域差分法為基礎之光學模型_應用於具奈微米結構之發光二極體

Optical Model Based on Finite Difference Time Domain Method for Analysis of Light-Emitting Diodes with Microstructures

李柏伸(Po-shen Lee)

指導教授 ： 張正陽 ； 伍茂仁

國立中央大學/理學院/光電科學研究所/碩士(2008年)

摘要

本篇論文利用有限時域差分法為演算法之基礎，用以分析發光二極體表面之為奈米結構之光學特性；針對其光粹取效率以及光型分布為主要研究方向。並且涵蓋製程與光致發光之角度量測系統量測之結果，用以交互比對模擬預測結果。研究內容包含四類不同用途需求之發光二極體設計，分別為：其一，蝕刻至n型氮化鎵層之近紫外光發光二極體表面結構以提高光粹取效率，過蝕刻側壁粹取主動層所發出之光能，進而縮短光在材料內之路徑以減少材料對光之吸收。其二，使用深蝕刻至n型氮化鎵層的梯型結構之傾斜側壁，粹取在n型氮化鎵層內橫向傳遞的能量並得到一蝙蝠翅膀型之光型分布。其三，利用蝕刻p型氮化鎵層產生之奈微米結構，將發光二極體之光型修整為均勻分布。其四，蝕刻沉積在p型氮化鎵層表面之氮化矽薄膜，產生微奈米結構以集中發光二極體之光型並且避免蝕刻所致之發光二極體電特性破壞。在上述四個案中比對量測與模擬結果，做為模擬模型之可信度驗證。

關鍵字

發光二極體 ； 有限時域差分法 ； 奈微米結構 ； 模型

並列摘要

In this thesis, a simulation model based on the FDTD algorithm is established to analyze the optical properties of light-emitting diodes such as light patterns and light extraction efficiency. Analyses focus on the effect caused by microstructures on surfaces of light-emitting diodes. Four LEDs for different demands including light extraction enhancement at near UV spectrum region, bat-wings for street lighting, uniform light pattern, concentrated light pattern, are shown theoretically and experimentally. Deep etching microstructures down to n-GaN layer is applied to enhance light extraction efficiency of near-UV light-emitting diodes by attenuating absorption caused by transparent conducting layers. Trapezoidal microstructures with deep etching on LEDs are applied to obtain a bat-wings light pattern by geometrically optical design. The microlens-like structures on p-GaN layer and Si3N4 film are applied to show a uniform intensity and a concentrated intensity in angular distribution, respectively. Also, 2.5-fold light enhancement is obtained in the former case through PL measurement; 1.15-fold, in the latter case. Based on comparisons between simulation and measurement results in these four cases, the credulity of this simulation model can be verified.

並列關鍵字

microstructures ； FDTD ； model ； LED ； optical peroperty

參考文獻

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