光子晶體氮化鎵發光二極體製作與分析

Fabrication and analysis of GaN photonic crystal LED

王柏人(Po-Jen Wang)

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)

摘要

中文摘要
氮化鎵系列的發光二極體已經成為紫外光到綠光發光二極體的主要材料。因為其寬能隙特性以及可改變鋁、鎵與銦成分比例去改變其能隙寬。高萃取效率的固態發光二極體目前在市場上有很大的需求，因為它的許多應用，包括全彩平面顯示器，汽車內外照明燈，以及一般照明。然而，雖然現在發光二極體的內部量子效率可以接近百分之百，但大部分的光都因為全反射而流失掉。
為了提高氮化鎵系列發光二極體之萃取效率，我們分別利用陽極氧化鋁模板技術以及電子束微影製程的技術來製作氮化鎵光子晶體發光二極體。根據我們的模擬結果，我們找出二維光子晶體氮化鎵發光二極體的最佳化設計，並根據此結果來製作之。在發光二極體的表面上蝕刻出六角形狀的孔洞來，其直徑為300奈米，晶格常數為500奈米，完成二維光子晶體發光二極體的製作。利用電性量測系統與微米級光激發光系統，研究光子晶體發光二極體的電學與光學特性。觀察出光子晶體發光二極體比較於一般發光二極體之發光效率有明顯的提升。並且我們發現以陽極氧化鋁模板及電子束微影技術製作的發光二極體，其正向電壓相對一般發光二極體都降低了。另外再研究其光學特性，觀察到光子晶體發光二極體的光激螢光強度比一般發光二極體提升了四倍，而其發光波長並沒有因為光子晶體結構而產生明顯偏移的情形。

關鍵字

光子晶體 ； 氮化鎵 ； 發光二極體

並列摘要

Abstract
GaN based light-emitting diodes (LEDs) have become the most popular material for UV to green light LEDs. Because it has high band gap characteristics and wavelength variation by changing the concentration of Al, Ga and In. Solid-state LEDs with high extraction efficiency are currently in great demand for various applications including full color flat displays, automotive interior and exterior lights, and general lighting. However, while the internal quantum efficiency of visible LEDs is close to 100%, most of the light is lost due to total internal reflection (TIR).
In order to enhance the extraction efficiency of GaN based LEDs, we separately fabricated GaN photonic crystal LEDs with anodic aluminum oxide (AAO) template and e-beam lithography technologies. According to our simulation result, we find out the optimum design of 2D photonic crystal GaN LEDs, and fabricate them according to this result. Hexagonal lattice PCs with diameter/periodicity of 300/500 nm were patterned by etching. Electronics measurement system and micro PL system are used to analyze the electrical and optical properties of PC LED. We observed that the enhancement of efficiency of PC LED is obvious higher than that of the as-grown LED. And we find that the forward voltage of LEDs which were fabricated with the AAO template and e-beam lithography technologies is lower than that of the as-grown LED. In addition we studied the optical properties of PC LED, and we observed the photo luminescence (PL) intensity of PC LED is enhanced four-fold relative to that of the as-grown LED, and there are not obvious shift of the peak wavelength.

並列關鍵字

photonic crystal ； GaN ； LED

參考文獻

[2] S. Nakamura, Science, 281, 956-961 (1998)

[3] Bernard Gil, Group III Nitride Semiconductor Compounds (Oxford, New York, 1998)

[4] S. Nakamura, Jap. J. Appl. Phys. 30, L1705 (1991)

[5] S. Nakamura et al. Jpn. J. Appl .Phys. 30, L1708 (1991)

[6] S. Nakamura, Takashi Mukai, and Masayuki Senoh, Appl. Phys. Lett. 64, 1687, (1994)