本論文主要在於研究有機金屬氣相沉積系統成長氮砷化銦鎵系列材料並應用於多接面太陽電池之研究；其中三五族三接面太陽能電池之轉換效率於2011年已創下超過40%之紀錄。而三五族太陽電池高轉換效率以及優越的抗輻射能力，使得其應用於外太空的酬載有很大的發展性。為了進一步提升傳統三接面太陽電池的效率，我們研究發展此種與鍺或砷化鎵晶格匹配且能隙接近1 eV的氮砷化銦鎵材料，該材料具有相當大的潛力可望作為下一個世代高效率太陽能電池的第四個接面，以提升整體轉換效率。從在砷化鎵基板上成長氮砷化銦鎵磊晶層開始，我們利用高解析X射線繞射儀分析成長材料之銦與氮的含量組成與能隙大小。為了使氮砷化銦鎵之吸收波長達到1240 nm並同時降低晶格常數的不匹配，必須調整TMIn/III與DMHy/VT之比例，進而控制銦與氮組成比例。藉由降低磊晶溫度、提升成長壓力與DMHy/VT比例可以提升原本較難溶入的氮原子組成比例。我們利用各個不同溫度下成長的未摻雜氮砷化銦鎵作為本質層以吸收太陽能頻譜中長波長的區段，製作雙異質接面p型砷化鎵/未摻雜氮砷化銦鎵/n型砷化鎵太陽能電池。進而以熱退火後處理改善氮砷化銦鎵材料特性，並以X射線光電子能譜分析氮砷化銦鎵退火前後之材料鍵結。量測元件效率顯示，經過退火處理之600°C成長氮砷化銦鎵磊晶層具有較佳的光電特性，太陽能電池轉換效率可到達4.46%。未來我們可嘗試著以氮砷化銦鎵太陽能電池作為第四個接面應用在磷化銦鎵/砷化鎵/1eV/鍺多接面太陽能電池元件結構中，更進一步地提升整體的效率。另外我們亦發展以砷化銦鎵/砷化鎵量子井結構延伸吸收波長，期望調整量子井組成而使得其吸收波長達到1eV，再將量子井結構置於本質層以形成p-i-n量子井太陽能電池。因此，我們可將量子井太陽能電池應用至磷化銦鎵/砷化鎵/1eV/鍺多接面太陽電池結構。而在有機氣相沉積系統磊晶過程中，可經由調整TMIn/III比例以及五三比來延伸吸收波長及改善磊晶品質；雖然增加TMIn/III比例有助於延伸吸收波段，但銦含量增加導致應力提升，因此量子井結晶品質和光特性變差，該問題可由增加五三比來改善。而後成長銦含量22%之砷化銦鎵/砷化鎵量子井太陽能電池。在固定本質層總厚度下，將其分成不同對數量子井；由實驗結果可知，當量子井對數增加時，光電流有大幅提升造成轉換效率從1.50 %提升到6.55%，且其40對砷化銦鎵/砷化鎵量子井太陽能電池之吸收波長已達到1100 nm (1.12 eV)。另外為了進一步延伸太陽電池吸收波長，於砷化銦鎵井層中摻入氮元素。其氮含量為4.3%之電池效率為2.48%，其吸收波長可延伸至約1300 nm (0.95 eV)；為了改善氮摻入劣化太陽電池特性，我們採用混合式量子井太陽電池結構，而量子井太陽電池效率提升至2.955%。
另一方面，為了更進一步提高太陽能電池轉換效率，我們亦應用不同形貌的氧化鋅奈米線/氧化鋁鋅層作為抗反射層並應用於傳統三接面太陽電池上，並探討其影響。儘管氧化鋁鋅層電特性十分優越，但其高反射率將會大幅減少入射光進入太陽電池之機會，故我們在氧化鋁鋅層上製作不同形貌氧化鋅奈米線，使得平均加權反射率可降低至12%，而三接面太陽電池轉換效率可從21％增加至26.2％。而在160倍光照下，其三接面太陽電池轉換效率可以提升到32％。

關鍵字: 太陽電池, 氮砷化銦鎵, 有機金屬氣相沉積系統

The main purpose of the dissertation was the investigation of InGaAsN material grown by metal organic vapor phase epitaxy (MOVPE) system and its application on multi-junction solar cell; the conversion efficiency of III-V compound triple junction solar cell have exceeded 40%. III-V solar cells with high conversion efficiency and superior radiation resistance, making applied to outer space payloads have great development. To further enhance traditional triple junction solar cell conversion efficiency, we have studied the growth of InGaAsN material with 1 eV band gap energy and lattice matching to GaAs or Ge substrate. The InGaAsN material with considerable potential in applying as the fourth junction is expected as the next generation of high-efficiency solar cells. In the InGaAsN material growth process, we used high-resolution X-ray diffraction (XRD) to analyze the composition and the band gap energy of InGaAsN. In order to extend the absorption wavelength region to 1240 nm while reducing the mismatch of the lattice constants, the TMIn/III and DMHy/VT proportion must be adjusted, and thereby control the composition ratio of indium and nitrogen. Via lower epitaxial temperature、larger growth pressure and higher DMHy/VT ratio, the nitrogen content of InGaAsN material could be upgraded. We have grown un-doped InGaAsN material under various growth temperatures as absorption layer to absorb long wavelength incident light, and fabricated the hetero-junction p-GaAs/u-InGaAsN/n-GaAs solar cells. To improve the the InGaAsN material properties, thermal annealing treatment was employed, and we used X-ray photoelectron spectroscopy (XPS) analysis to analyze the InGaAsN material bonding before and after annealing. From the measurement result, the InGaAN material annealed at 600°C has superior optical and electrical characteristics, and the conversion efficiency of InGaAsN solar cell would reach 4.46%. In addition, we have also developed the InGaAs/GaAs quantum well structure to extend the absorption wavelength, and we applied quantum well structure in the intrinsic layer to form p-i-n quantum well solar cells. Therefore, we would apply quantum well solar cell on InGaP/GaAs/1eV/Ge multi-junction solar cell structure. While quantum well structure growth process by MOVPE, we would adjust TMIn/III ratio and V/III ratio to extend the absorption band edge and crystalline characteristics. Increasing TMIn/III ratio is helpful to extend absorption band edge, but large Indium content would lead to increasing strain caused by lattice mismatch. Therefore, increasing TMIn/III ratio would result in the deterioration of the crystal quality and optical properties of the quantum wells, and the deterioration of quantum well characteristics would be recovered by increasing V/III ratio. Then we grow the InGaAs/GaAs quantum well solar cells with indium content of 22%. Fixed total thickness of the intrinsic layer, divided into different pairs of sub-quantum wells; the result indicates the increasing of quantum well pairs would lead to significant photo current enhancement, the conversion efficiency would increase from 1.5% to 6.55%, and the absorption band edge of 40 pair InGaAs/GaAs quantum well solar cell have reached 1100 nm (1.12 eV). In order to further enhance the solar cell absorption band edge, we incorporate nitrogen into InGaAs well layer. The nitrogen content of InGaAsN/GaAs quantum well solar cells is 4.3% and the conversion efficiency of that is 2.48%, and its absorption band edge would be extended to 1300 nm (0.95 eV). For improving solar cell characteristics deterioration caused by nitrogen incorporation, we applied hybrid quantum well solar cell structure and the hybrid quantum well solar cell conversion efficiency would be enhanced to 2.955%.
On the other hand, in order to further improve the solar cell performance, we applied different morphologies of ZnO nanowires/ZnO:Al layer as anti-reflective layer on the multi-junction GaAs solar cell structure and explored its effects. We have grown the nano-structural ZnO/ZnO:Al film as anti-reflection coating layer on triple junction solar cells and subsequently characterized their performances. In spite of the superior electrical characteristics of ZnO:Al layer deposited by radio frequency sputtering, a large reflectance of ZnO:Al film on GaAs leads to reduction of incident light. With nano-structural ZnO/ZnO:Al antireflection coating layer implemented, the conversion efficiency of GaAs based triple junction solar cells have enhanced from 21 to 26.2% under AM 1.5 global illumination (100 mw/cm2) and it can be further improved up to 32% with 160-sun illumination.

Key words: solar cells, InGaAsN, MOVPE

Chapter 1
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Chapter 4
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Chapter 5
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Chapter 6
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