臺灣博碩士論文加值系統

本論文研究中將對發光二極體(Light-Emitting Diode, LED)的主動區作改變，以實現不同的波長，分別為藍光、綠光與近紫外光三種，主要差異在於量子井的銦(In)組成比不同。實驗中設計三種發光二極體的主動區之量子井(Well)與位障(Barrier)層，分別為GaN/In0.4Ga0.6N、GaN/In0.23Ga0.77N與Al0.07Ga0.93N/In0.1Ga0.9N，並命名為Green、Blue與NUV，探討其光電特性與溫度效應。
在實驗中發現，Green LED在工作電流350 mA下的光輸出功率141 mW、外部量子效率衰減了24 %，是三個樣品中最差的，其銦組成比例最高，因此在量子井區內的應力極化效應最嚴重，導致井區內的量子侷限史塔克效應(Quantum Confined Stark Effect, QCSE)，這會減少載子的輻射復合率；另外，銦聚集(In-rich cluster)也較嚴重，形成較多的侷限能態(Localization state)，當電流增加時會使歐傑復合(Auger recombination)的機率增加，因此外部量子效率衰減最嚴重。
在溫度效應的量測部分，主要分析三種樣品在高溫時對於溫度的依賴性，當環境溫度升高後，載子會因為溫度而獲得額外能量後逃脫量子井，發現侷限能態較多的樣品可以有效的抑制載子的溢流。另外，在低溫環境下可以透過光強度的變化觀察三種不同主動區內的載子傳輸情形；從波長的變化也可以觀察到三個樣品的侷限能態情形。
本研究之方法，主要是透過溫度的改變來探討載子在量子井區內的行為，我們可以得知氮化物系列的發光二極體應用在不同波長，會因為井區的銦組成比改變而造成不同的光電特性。

In this research, we investigated multiple quantum well with different indium composition of Green, Blue and Near Ultraviolet light-emitting diodes. The molar composition of three LEDs are GaN/In0.4Ga0.6N, GaN/In0.23Ga0.77N, and Al0.07Ga0.93N/In0.1Ga0.9N, respectively. Following, we will measure and discuss the optical properties and temperature-dependence.
The measurements result of light output power, external quantum efficiency and efficiency droop show Green LED has worst optical properties. Because Green LED has the worst QCSE effect which caused by high indium composition and reduce radiative recombination. The serious In-rich cluster, localization and auger recombination was originated from the higher indium composition.
We analyze the temperature effect for three samples at high and low temperature, respectively. When the ambient temperature rises, the carrier will escape from the quantum wells after gaining additional energy by the temperature, and it is found that the sample with more localization state can effectively suppress the carrier overflow. In addition, the low ambient temperature can observe through the light intensity of this three different active regions of the carrier transport situation. The localization state of the three samples can also be observed from the variation of wavelength.

摘要 iii
ABSTRACT iv
誌謝 v
目次 vi
圖目錄 viii
第一章 序論 1
1.1 發光二極體背景介紹 1
1.2 研究動機 2
1.3 整體架構 10
第二章 基礎理論與元件製作 11
2.1 氮化鎵系列材料特性介紹 11
2.2 氮化鎵發光二極體之發光原理 13
2.3 應力與極化效應 15
2.4 侷限能態 18
2.5 內部量子效率 19
2.6 影響效率衰減之因素 21
2.6.1 極化效應 22
2.6.2 載子注入效率 24
2.6.3 歐傑復合 26
2.6.4 磊晶品質 27
2.6.5 熱效應 29
2.7 氮化鎵發光二極體元件製作 30
2.7.1 發光二極體磊晶製程 31
2.7.2 發光二極體前段製程 32
2.7.3 發光二極體後段製程 33
2.8 實驗樣品架構 34
第三章 光電特性量測與分析 35
3.1 電特性量測與分析 35
3.2 光特性量測與分析 36
3.2.1 電流-光輸出功率量測與分析 36
3.2.2 外部量子效率與衰減 37
3.2.3 半高寬 40
第四章 溫度效應之電致發光量測與分析 42
4.1 高溫之電致發光量測與分析 42
4.1.1 溫度-電壓特性量測與分析 42
4.1.2 溫度-光功率特性量測與分析 44
4.2 低溫之電致發光量測與分析 47
4.2.1 溫度-電壓特性量測與分析 47
4.2.2 溫度-光強度特性量測與分析 50
4.2.3 波長變化 52
第五章 結論與展望 55
5.1 結論 55
5.2 未來展望 56
參考文獻 57

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