本論文主要研究的晶體材料可分為兩類，其一類是二維有機無機混成鹵化鈣鈦礦結構，使用緩速蒸發恆溫溶液生長技術成長，藉由控制無機層的層數(n)可改變其吸收與放光的波長位置，n越大則吸收與放光波長越往紅移。此類晶體為量子井(Quantum well) 結構，從熱調制反射光譜 (thermoreflectance, TR) 中，我們發現除了晶體的主要激子躍遷訊號外，在能隙訊號邊緣後有夫蘭茲 • 開爾西振盪 (Franz Keldysh Oscillation, FKO)，我們推測原因為其有機層的電雙極在溫度微擾下會有較大的改變，導致接面狀態數不同造成能帶傾斜形成內建電場，進而量測出FKO譜形，溫度下降時載子濃度會隨著減少，而內建電場也會變小。在比對文獻下，將激子躍遷位置分為A、B和C三區，在低溫15K時，無機層為一層(n = 1)的低溫躍遷位置分別約為2.6 eV、3.5 eV與4.3 eV，並從伴隨的FKO分析出其內建電場約為FA= 720±60 kV/cm、FB= 1000±80 kV/cm與FC= 410±60 kV/cm，而無機層為二層(n=2)時，其躍遷位置分別約為2.3 eV、3.2eV與4.0eV，並從伴隨的FKO分析出其內建電場為FA= 430±30 kV/cm、FB= 520±20 kV/cm與FC= 453±50 kV/cm。在光激發螢光實驗中(Photoluminescence, PL)，使用為波長266 nm的雷射作為激發源，可以量測到與TR光譜相對應的發光位置。在溫度相依實驗中，我們可以觀察到在15 K時有自由激子(FXA, FXB)、束縛激子(BXA, BXB)、缺陷態(BXDT) 與施子受子對 (DAPB)。隨著溫度上升，束縛激子(BXA, BXB) 會逐漸變小至消失，而由自由激子(FXA, FXB)主導逐漸紅移。其中最特別的是在特定溫度範圍內，此類晶體會有一個很大的相轉變，造成訊號產生極大的偏移，為了更細緻的觀察，本論文以每1K作為區間進行量測，觀察其消長與相轉變。
本論文研究的另一類晶體為二維層狀晶體二硫化鉿(HfS2) 與三硫化鉿(HfS3)，其晶體由化學氣相傳導法(Chemical Vapor Transport, CVT) 生成，其皆為鉿(Hf)與硫(S)組成，可藉由控制元素比例與成長溫度獲得。進行一系列的結構分析實驗，HfS2為六方晶系結構(Hexagonal)，其外觀為紅色透明且層狀排列。HfS3則為單斜晶系(Monoclinic)，其外觀為橘色透明且形狀為帶狀(belt)，此晶體有極明顯的光學異向性，本論文進行角度相依拉曼光譜量測，以觀察其振動模式變化。HfS2 與HfS3在熱調制反射光譜中可量測到室溫能系位置分別為2.0 eV與2.1 eV，隨著溫度降低，能隙訊號會往高能量移動，此結果也與穿透光譜所測得的相符合。本論文提出了二維有機無機混成鹵化鈣鈦礦結構以及層狀結構硫屬鉿化物的光學特性研究，相信對於不管是太陽能電池、光電元件或者是光學透鏡上的應用都會基本上的了解。

In this master’s dissertation, the crystals mainly studied could be divided into two categories, one of which is Ruddlesden–Popper perovskites (RPP) crystal. The thermoreflectance (TR) spectra show Franz Keldysh oscillations (FKOs) after the band edge. This phenomenon happened because of the dipole orientation of the organic layers. A build-in electric field is therefore inferred to generate at the junction. And this built-in electric field will become smaller as the temperature decrease. The excitonic transitions of RPP are separated into three regions A, B and C band. At 15 K, the excitonic transitions of the crystal (n=1) are 2.6 eV, 3.5 eV and 4.3 eV respectively. By analyzing the following FKOs, these built-in electric fields are FA= 720±60 kV/cm, FB= 1000±80 kV/cm and FC= 410±60 kV/cm. In the other side, the excitonic transitions of the crystal (n=2) are 2.3 eV, 3.2 eV and 4.0 eV and their built-in electric fields are FA= 430±30 kV/cm, FB= 520±20 kV/cm and FC= 453 ± 50 kV/cm. In the photoluminescence (PL) results, the excitonic transitions are matched with the TR results. At 15 K, we can observe free excitons (FXA, FXB), bound excitons (BXA, BXB), defect states (BXDT) and donor-acceptor pairs (DAPB). When the temperature is increased from 15 K to 300 K, the bound excitons (BXA, BXB) is gradually ionized until disappear, and the free excitons (FXA, FXB) have the red shift phenomenon. Especially, in the specific temperature range, the excitonic transitions have an intensely shift because of the phase transitions. For detailed observing this process, we measured it per 1 K close tophase-transition temperature. The other crystals are HfS2 and HfS3 grown by Chemical Vapor Transport method. The structures of these materials are well identified by energy dispersive X-ray spectroscopy, X-ray diffraction and Raman scattering spectra. HfS2 and HfS3 are classified as layered type semiconductors that crystalize in one-layer-trigonal (1T) phase and monoclinic structure, respectively. Layered HfS3 has strongly anisotropic properties. Due to its anisotropy properties, we did orientation-dependent in Raman spectra to observe its vibration mode. We use TR and Tr to do optical characterizations. In the TR results, the energy bandgap of HfS2 and HfS3 are 2.0 eV and 2.1 eV at 300 K respectively. Decreasing the temperature, the bandgaps have the blue shift phenomenon. These results are also matched with the transmittance results. We studied the optical properties of RPP, HfS2 and HfS3. We believed that it will be basically comprehended for applications of the materials as solar cells, optoelectrical devices, optical lenses, etc.

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