本論文之研究目的著重於延伸砷化銦鎵相關量子井結構之吸收波長，期望能達到1.25 eV或1 eV，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，我們可以將這些具有1.25 eV或1 eV吸收波長的量子井太陽能電池應用到未來的多接面太陽能電池中以提升整體效率，如InGaP/GaAs/1 eV/Ge或是InGaP/1.25 eV/Ge等兩種多接面結構皆適用。在研究中，我們利用了高解析X射線繞射儀以及光激發螢光光譜等量測設備來探討所成長的磊晶層品質以及組成。
首先，我們利用有機金屬氣相沉積法成長InGaAs/GaAs量子井於砷化鎵基板上。接著我們藉由調整TMIn/III比例以及五三比來延伸吸收波長以及改善磊晶品質。我們發現雖然增加TMIn/III比例有助於延伸吸收波段，但由於應力同時提升，因此使得量子井的結晶品質和光特性變差。此問題經由實驗可知可由增加五三比來改善，因此我們最後成功地成長了銦含量達22% 之InGaAs/GaAs量子井結構。由於砷化銦鎵會造成壓縮應力，因此我們選擇以氮含量為6%的氮砷化鎵利用其伸張應力來補償以形成In0.22GaAs/GaAsN0.06應力補償型量子井結構。實驗發現，我們利用不連續地成長砷化銦鎵與氮砷化鎵及在兩者之間加入砷化鎵緩衝層皆能有效提升介面品質與特性。
我們接著利用量子井結構成長In0.22GaAs/GaAs量子井太陽能電池。本質層總厚度不變的情形下，我們將它分為10對、20對和40對之In0.22GaAs/GaAs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1.499%提升到6.552%。此外，In0.22GaAs/GaAs量子井太陽能電池之吸收波長已達到1100 nm (1.12 eV)。我們同時嘗試成長In0.22GaAs/GaAsN0.06應力補償型量子井太陽能電池，但其轉換效率不如預期的提升，推論其原因乃採用高氮含量之氮砷化鎵所致。
我們亦研究In0.22GaAsNx/GaAs量子井太陽能電池，目的是為了更進一步延伸吸收波長。氮含量為3.3%與4.3%之電池效率為2.482%與2.955%，因4.3%氮含量之氮砷化銦鎵與砷化鎵較為晶格匹配之故。其吸收波長可延伸至約1300 nm (0.95 eV)。
未來，我們可嘗試將In0.22GaAs/GaAs或In0.22GaAsN0.043/GaAs量子井太陽能電池應用到InGaP/1.25 eV/Ge或者是InGaP/GaAs/1 eV/Ge等多接面太陽能電池中。

In this thesis, the main purpose of our research is focused on extending the absorption edge of InGaAs-related quantum well structures to 1 eV or 1.25 eV. Then we can grow p-GaAs/i-(QWs)/n-GaAs quantum well solar cells by MOVPE. Therefore, we can apply these quantum well solar cells to form the next-generation multi-junction solar cells such as InGaP/GaAs/1 eV/Ge or InGaP/1.25 eV/Ge multi-stacking structures in the future. Plenty of material characterization techniques such as high resolution X-ray diffraction and photoluminescence system have been used to study the quality and characteristics.
First, we tried to grow the InGaAs/GaAs quantum wells on GaAs substrates by MOVPE. We adjusted the TMIn/III ratio and V/III ratio to obtain long-wavelength absorption and better quality. When the TMIn/III ratio was increased, the absorption edge of InGaAs/GaAs quantum wells could be extended but the crystalline and optical qualities were deteriorated by enhancement of strain. Through increasing the V/III ratio, the overall qualities could be improved. We grew the In0.22GaAs/GaAs quantum wells consequently.
Due to compressive strain from In0.22GaAs, we adopted GaAsN0.06 to fabricate the In0.22GaAs/GaAsN0.06 strain-compensated quantum wells in order to reduce total strain. The InGaAs and GaAsN layers owned better quality when grown discontinuously. By inserting GaAs buffer layers between InGaAs and GaAsN layers, the interface quality was enhanced because of smoother surface.
In the following, we grew the In0.22GaAs/GaAs strained quantum well solar cells. The total thickness of intrinsic layer was fixed and divided into 10, 20 and 40 pairs of InGaAs/GaAs quantum wells. With more pairs of quantum wells, the conversion efficiency was enhanced from 1.499% to 6.552%. And the absorption edge of solar cells was extended to approximately 1100 nm (1.12 eV). Then we tried to grow In0.22GaAs/GaAsN0.06 strain-compensated quantum well solar cells. The efficiency was unanticipated low owing to such high nitrogen concentration.
Final, we studied the In0.22GaAsNx/GaAs quantum wells in order to further extend the absorption edge to longer wavelength region. So we grew the In0.22GaAsNx/GaAs quantum well solar cells with 3.3% and 4.3% nitrogen content. We found that conversion efficiency was increased from 2.482% to 2.955% when the nitrogen content was increased from 3.3% to 4.3%. The reason for the enhancement of efficiency was that the In0.22GaAsN0.043 was more lattice-matched with GaAs so that the amount of defects was less than In0.22GaAsN0.033. Furthermore, the absorption edge of In0.22GaAsNx/GaAs quantum well solar cells was successfully extended to about 1300nm (0.95 eV).
In the future, the long-term goal for our research is to develop the InGaP/1.25 eV/Ge or InGaP/GaAs/1 eV/Ge multi-junction solar cell by applying InGaAs/GaAs or InGaAsN/GaAs quantum well solar cells to improve the performance of solar cells.

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