臺灣博碩士論文加值系統

近年來，雖然氮化鎵發光二極體的發光效率隨著磊晶及製程技術的發展而持續增加，但若與傳統照明系統比較可知，其發光強度和效率仍低了許多。
本研究先以液相沉積法於氮化鎵基材上成長二氧化矽薄膜，並分析二氧化矽薄膜及其鋁/二氧化矽/氮化鎵金氧半二極體的各項特性，接著使用溫差法、熱處理、光化學處理、硫化處理等方法來改善二氧化矽特性及得到理想的成長參數。在此研究基礎下探討液相沉積法成長二氧化矽的成長機制，進而在氮化鎵發光二極體磊晶片上成長半球形二氧化矽微透鏡來增加光取出效率，並使用上述熱處理等方法，再輔以覆晶技術使氮化鎵發光二極體擁有更高的光取出。比較半球形二氧化矽微透鏡對傳統式及覆晶式發光二極體的影響，在此發光二極體上覆蓋環氧樹脂而產生的影響也將納入討論。
由於二氧化矽微透鏡與環氧樹脂的折射係數相當接近，具有二氧化矽微透鏡的氮化鎵發光二極體之光取出效率及其射出光角度分佈會在環氧樹脂覆蓋後衰退，因此，我們也試著在氮化鎵發光二極體上以液相沉積法成長氧化鋅薄膜及氧化鋅晶柱，使發光二極體能在環氧樹脂覆蓋\後能保持或進一步增加氧化鋅產生的光取出增益。

In recent years, even though the light output of GaN-related LED continues to increase, the brightness is still low compared to conventional lighting systems and it is necessary to further improve the light extraction of LEDs.
In this study, the characteristics of LPD-SiO2 film and Al/SiO2/GaN MOS diode were investigated in advance of the formation of SiO2 micro structure for improving the oxide quality and controlling the deposition parameters. Temperature-difference method, post-annealing treatment, photochemical treatment, sulfurated treatment and etc. were used for the purposes of better properties of the MOS structure and the LED. To obtain higher light extraction efficiency of GaN LED, hemispherical SiO2 microlens was formed on the conventional and the flip-chip LEDs. The deposition mechanism had been developed to obtain the further improvements on the electrical and optical properties. The influences of epoxy encapsulation on the LEDs without and with microlens were also studied.
Considering the refractive index of SiO2 is close to that of the epoxy, the enhancements of light extraction efficiency and angular optical distribution of GaN LED by using SiO2 microlens will be degraded after encapsulating. Therefore, we also tried to deposit ZnO film and rod on GaN LED by LPD method to maintain or further enhance the light extraction efficiency of GaN LEDs by the combining the micro structure and the epoxy encapsulation.

Acknowledgment ……………………….…………………..……...…..…..….I
Contents …………………………………………………….…..………….….IV
List of Figures ………………………………………………………..……….IX
List of Tables …………………………………………………….……..…...XIV
Abstract ………...…………………………………………………….…..…..XV

Chapter 1 Introduction …………………………………………………….….1
1-1 Background of GaN-related Materials ……………………………….…1
1-2 GaN-Based LED …………………………………….……………….…2
1-2-1 Evolution of LED ………………………………………………… .3
1-2-2 Structure of GaN-based LED ……………………..…….………….3
1-2-3 Problems of GaN-based LED ………………………………….…...4
1-3 Motivations of SiO2 on GaN blue LED ……………………….…………6
1-4 Liquid Phase Deposited SiO2 ……………………………….…………...8
1-5 Pre- and Post-Treatments on SiO2/GaNLED …………………..…..…….9
1-5-1 Temperature-Difference Method ……….………………..…….........9
1-5-2 Photochemical Treatment ……….……………………….…...........10
1-5-3 Sulfurated Treatment ……….………………...…………………....12
1-5-4 Post-Annealing Treatment ……….…………………..……….........12
1-5-5 Flip-Chip Technology ……….………………..…………….…......13
1-5-6 Epoxy Encapsulation ……….………………………….…….........14
1-6 LPD-ZnO on GaN LED ………..….……………………...……….........15

Chapter 2 Experiments ………………………………………………….…..24
2-1 LPD System …………………………….………………………….…..24
2-2 GaN Blue LED …………………………………………………….…..25
2-3 LPD Processes ………………………..………………………………...25
2-3-1 Substrate Cleaning Procedures …………………………………….25
2-3-2 Preparation of Deposition Solution …………………...…………...26
2-4 Pre- and Post-Treatments ………………………………………….…....27
2-4-1 Photochemical Treatment ……………………………...…………..27
2-4-2 Sulfurated Treatment …………………….……………..………….28
2-4-3 Post-Annealing Treatment …………………………………...…….28
2-4-4 Flip-Chip Technology ………………………………………….….29
2-4-5 Epoxy Encapsulation ……………………………..……………….29
2-5 Fabrication of MOS diode ……………………………….………….30
2-6 Characterization ……………………………………………….……….30
2-6-1 Physical and Chemical Properties …………….………….……….30
2-6-2 Optical Properties ………………………………..……….……….31
2-6-3 Electrical Properties ……………………………………....……….32

Chapter 3 Characteristics of LPD-SiO2 Film on GaN ……………………....36
3-1 Characteristics of LPD-SiO2 Film on GaN ……………………………..36
3-1-1 Deposition Rate …………………………………………….….…..36
3-1-2 FE-SEM Morphology ……………………...…………………...….37
3-1-3 XRD Spectrum …………………...…………………………..….37
3-1-4 XPS Spectrum and SIMS Depth Profile ……………………..……37
3-1-5 J-E Curve ……………………...…………………………………..38
3-1-6 C-V Curve ……………………...………………………………….39
3-2 Characteristics of TD-LPD-SiO2 on GaN ………...………………...….40
3-2-1 Deposition Rate ……………………...…………………………….40
3-2-2 XPS Spectrum and SIMS Depth Profile ……………..……………41
3-2-3 J-E Curve ……………………...…………………………….…….41
3-2-4 C-V Curve …………………….…………………………..……….41
3-3 N2O Post-Annealing Treatment ………………………..……...……….42
3-3-1 XPS Spectrum ……………...…………………………………..…42
3-3-2 J-E Curve ……………………...…………………………….…….43
3-3-3 Refractive Index and C-V Curve …………………….………...….43
3-4 Photochemical Treatment …………………...………………………….44
3-4-1 Schematic LPD-SiO2 on GaN …………………………...…...……44
3-4-2 FE-SEM Morphology ………………………………………….….45
3-4-3 J-E Curve ……………………...…………………………………..46
3-4-4 C-V Curve ……………………...………………………………….46
3-5 Sulfurated Treatment …………………...………………………...…….47
3-5-1 XPS Spectrum ……………………...………………………..…….47
3-5-2 J-E Curve and XPS Spectrum ……………………...…………...…47
3-5-3 C-V Curve ……………………...………………………………….48
3-6 Tentative Summary …………………...…………………………..…….49

Chapter 4 Characteristics of TD-LPD-SiO2 on GaN LED ……………….…76
4-1 Characteristics of SiO2 Film on GaN LED ………………………….…76
4-1-1 Fresnel’s Loss ……………………...………………………..…….76
4-1-2 N2O Post-Annealing Treatment ……………………………….…...77
4-1-3 Photochemical and Sulfurated Treatments ……………………...…78
4-1-4 GaN Flip-Chip LED ……………………...………………………..79
4-2 Characteristics of TD-LPD-SiO2 Microlens on GaN LED ………….…79
4-2-1 Mechanisms of LPD-SiO2 ……………………...………………….80
4-2-2 SiO2 microlens on GaN LED ……………...………...…………….81
4-2-3 N2O Post-Annealing Treatment ………………………………...….83
4-2-4 Concentration of TD-LPD Solution ……………………………….84
4-2-5 Incorporation of NH4OH Solution ………………………………...85
4-2-6 Photochemical Treatment ……………………...…………….……86
4-2-7 Epoxy Encapsulation ……………………...……………………….88
4-2-8 GaN Flip-Chip LED ……………………...…………………….….89
4-3 Tentative Summary …………………...………………………………...91

Chapter 5 Characteristics of LPD-ZnO on GaN LED ………………….….111
5-1 LPD-ZnO on GaN LED …………………...…………………………..111
5-1-1 FE-SEM Morphology ……………………...…………………..…112
5-1-2 Crystal Structure ……………………...……………………….….112
5-1-3 Schematic LPD-ZnO on GaN ……………………………………113
5-1-4 EL Spectrum ……………………...……………………………....114
5-1-5 Light Output Power and Angular Optical Distribution ………..…114
5-2 Epoxy Encapsulation …………………...…………………………..…115
5-2-1 EL Spectrum ……………………...………………………………115
5-2-2 Angular Optical Distribution ……………………………..………115
5-3 Tentative Summary …………………...……………………………….116

Chapter 6 Conclusions ………………………………………………..……124

References ……………………………………………………………………126
Vita ………………………………………………………………….……......132
Publication List ………………………………………………………………133

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