高效率發光二極體的光學模擬

Optical simulation for high efficiency LED

許裕宗(Yu-Zong Shu)

指導教授 ： 黃惠良

國立清華大學/電機資訊學院/電子工程研究所/碩士(2006年)

https://doi.org/10.6843/NTHU.2006.00222

摘要

發光二極體具有很多的優點例如長的使用時間、高效率、高可靠度、指向性、對震動和撞擊的不敏感度、可微小封裝等。 近幾年來,，由於螢光燈將在不遠的將來被取代，高效率的白光發光二極體獲得極大的注目。 現今由於在磊晶技術的成熟發展下，具有高數值的內部量子效率的發光二極體已經可被獲得。然而發光二極體的光萃取效率經常低於40%。 另外，當發光二極體在各式各樣的應用特別是在固態照明的領域，遠場輻射場型變成一個非常重要的問題。
為了提高覆晶發光二極體的光萃取效率，我們在藍寶石層及氮化鎵層之間設計不同粗化程度的表面結構。 這個粗化的表面結構可以減少發光二極體中光的全反射並增加光從晶片中逃脫的機率。 而為了預測發光二極體的遠場輻射場型，我們也針對實際封裝過的發光二極體設計光學模型。
藉著這些光學模擬,我們可以得到一具有較高光萃取效率的發光二極體，並且可被適用製造。 我們也可以根據各種的照明應用來設計不同型式的發光二極體封裝。 這部論文中的所有光學模型及模擬都建立在一個線追跡的軟體TracePro。

關鍵字

發光二極體 ； 光學模擬

並列摘要

Light emitting diode (LED) has many advantages such as long lifetime, high efficiency and reliability, directional, insensitive to vibration and shocks, compact forms. In the recent years, high efficiency white LEDs have gained much interest because the replacement of fluorescent lamps will be realized in the near future. Nowadays the high internal quantum efficiency of LED has already been obtained because of the matured growth of epitaxy technology. However, the light extraction efficiency of LED is always less than 40%. In addition, when LEDs are applied to various applications especially in the field of solid-state lighting, the far-field radiation patterns of LEDs becomes a very important issue.
In order to enhance the light extraction efficiency of a flip chip LED, we design the different rough surface structures between the sapphire layer and GaN layer. The roughed surface structure can reduce the total internal reflection (TIR) inside the LED and increase the probability of light escape from the chip. In order to predict the far-field radiation patterns of LEDs, we also design the optical model for practical packaged LED.
After the optical simulations, we can get a higher light extraction efficiency LED chip. We also can design the various form of LED packages for any kind of lighting applications. All of the optical models and simulations in this thesis are built by ray-tracing software (TracePro)

並列關鍵字

LED ； optical simulation

參考文獻

Chapter 1

[1.1] Mitsuo Fukuda, ‘’Optical Semiconductor Devices ’’, John Wiley & Sons , 1999

[1.2] N. Holonyak Jr. and S. F. Bevaqua, ‘‘Coherent (visible) light emission from

Semiconductor, Vol. 59, 2001.

[1.4] Stephen Johnson, ‘‘LEDs—An Overview of the State of the Art in Technology