摘要
本論文旨於探討半導體太陽能電池材料的特性分析，其主要研究的材料分別為下列三種：氮化銦，加碼(γ)相的硒化銦和磷化鎵銦為主的三接面太陽能電池元件。首先，在論文的第一部份，我們試以不同層數的緩衝層研究氮化銦磊晶層成長在矽基版上的結果，由光激螢光和時間解析光激螢光譜得知三層緩衝層的光學特性為最佳。根據X光繞射光譜和穿透式電子顯微鏡得知氮化銦和矽基版的應力，經由緩衝層得到釋放，故材料特性也是以三層緩衝層為最佳。 第二部分利用光激螢光實驗討論氮化銦磊晶層的載子鬆弛機制。由實驗中獲得電子氣體溫度的變化，且在不同載子濃度下，電子損失能量鬆弛至導帶的主要機制，能以不同比例的電子-光學聲子和電子-聲學聲子之間的交互作用理論模型來解釋。在15K溫度下，氮化銦不同載子濃度的聲子生命期與理論所得的生命期有所差異，此差異可能歸因於熱聲子效應的作用。 第三部分，以有機化學氣相磊晶的方式，在矽基版上成功的成長硒化銦磊晶層和奈米柱兩種不同結構，藉由X光繞射、掃瞄式電子顯微鏡、穿透式電子顯微鏡和選區電子繞射等實驗，證實此硒化銦為單晶結構。由能量改變的光激螢光實驗分別探討硒化銦磊晶層和奈米柱的載子鬆弛機制。在15K溫度下，藉由電子氣體溫度的變化，可得到一個聲子的能量，再以偏極化的拉曼光譜實驗進行驗證，發現有相同大小的聲子能量，於是定義此能量為光學聲子。 第四部分，由光激螢光、時間解析光激螢光、光電流及電流-電壓等實驗，研究經快速熱退火與表面塗佈奈米金團簇的三接面(InGaP/InGaAs/Ge)太陽能電池。在快速熱退火處理後，材料中磷化鎵銦作用層的品質有提升現象，這是因為熱退火後，磷空缺的複合體被消除的關係。當入射光能量大於 1.8 eV 時，光電流也在熱退火後有增加的現象，且太陽能電池的光電轉換效率增加 2 %。當太陽能電池表面塗佈奈米金團簇後，發現光激螢光強度、載子生命期分別增加約 1.5 倍與 6 倍。利用Mie 理論可模擬出散射因子與波長的關係，且光激螢光強度提升的程度與理論模擬相符，所以螢光強度提升是因為奈米粒子增加散射率的關係。
並列摘要
This dissertation is devoted to the electronic and optical properties of semiconductor solar cell materials. The materials investigated include the InN, γ-In2Se3, and InGaP/GaAs/Ge three junction solar cells. The first part of the dissertation is investigating the effect of InN epilayer grown on Si substrate with different buffer layers. The InN epilayer grown on three buffer layers has the best optical quality by studying the photoluminescence (PL) and time-resolved PL (TRPL). According to the x-ray diffraction (XRD) measurements and transmission electron microscopy (TEM), the strain has been reduced between the InN epilayer and the Si substrate by using three buffer layers. Therefore, the InN epilayer has the best structural quality by growing three buffer layers. In the second part, the energy relaxation of electrons in InN epilayers is studied using PL measurements. It is found the measured electron temperature variation in different concentration can be explained by a model based on the energy relaxation of electrons due to both longitudinal optical (LO) phonon and acoustics phonon scattering. Under 15 K, the InN phonon lifetime obtained from experiments is higher than that from the theoretical calculations. This deviation is attributed to the presence of the hot phonon effect. The third part describes that the single phase γ-In2Se3 epilayers and nanorods on Si substrates were successfully grown by the metalorganic chemical vapor deposition (MOCVD). According to the XRD, high-resolution transmission electron microscopy (HRTEM) and selected-area electron diffraction (SAED), we demonstrated the grown γ-In2Se3 is the single crystal structure. It is found that the emission of the LO-phonons is the main energy loss process for hot electrons in -In2Se3 epilayers. The Raman peak at 151 cm-1 in -In2Se3 can be assigned to the LO-phonon mode. In the last part, we studied the PL and time-resolved PL of three-junction InGaP/InGaAs/Ge solar cells following rapid thermal annealing (RTA) and the incorporation of Au nanoclusters. The improvement of material quality in the InGaP active layer after RTA is evident from the PL and spectral response. When the annealing temperature is 300 oC, the PL intensity and carrier lifetime is maximum, which are respectively increased by about a factor of 2 and 5 compared with that of the untreated sample. We suggest that the removal of the phosphorusvacancy-related complexes may be responsible for improvement of the material quality after RTA. The power conversion efficiency is creased by 2 % after the 300 oC RTA treatment. In addition, the PL intensity (decay time) of the InGaP active layer in the triple-junction solar cell is increased by 1.5 (6) times after incorporation of gold nanoclusters. Based on the Mie scattering, the scattering factors of the gold nanoclusters as a function of wavelength were calculated. It is found the experimental enhancement of luminescence as a function of wavelength is in good agreement with the calculated results from the Mie scattering. We therefore suggest that the scattering of the gold nanoclusters is responsible for the enhancement of luminescence.