本論文利用化學氣相傳導法 (Chemical vapor transport method, CVT) 成長硫化鎵晶體，目前成功成長出Ga2S3晶體，之後進行晶體結構與光學特性分析。藉由能量散佈儀 (Energy dispersive X-ray spectrometer, EDS) 量測可以確定成長材料之元素比與預期相符合。而利用X-ray晶格繞射 (X-ray diffraction, XRD) 以及拉曼散射光譜 (Raman scattering spectra) 分析可確定Ga2S3為單斜結構 (Monoclinic structure)。
光學量測上，從熱調制光譜 (Thermoreflectance, TR) 以及穿透實驗 (Transmittance) 可觀察出此Ga2S3為直接能隙半導體，在300 K下藉由熱調制光譜可發現三個躍遷分別在3.07 eV、3.24 eV及3.29 eV，稱為A、B及C，進而執行熱調制光譜之溫度相依實驗，發現此三個躍遷訊號的溫度-能量移動幅度不同，從20K-300K分別移了約240 meV、170 meV及150 meV，再藉由極化相依的熱調制光譜實驗，得知此B與C有極化相關性，因此判斷此三個訊號為不同的來源。由光激發螢光光譜 (Photoluminescence, PL) 的結果，可觀察到許多低於能隙的發光訊號，故可推斷樣品有缺陷態存在，在溫度相依的PL實驗中在近能隙位置觀察到束縛激子及自由激子的訊號。藉由本論文之研究，對Ga2S3晶體的能帶結構與光學特性，能有更進一步的了解。

Crystalline Ga2S3 has been grown by chemical vapor transport method using ICl3 as a transport agent. X-ray diffraction and Raman spectroscopy confirmed monoclinic structure for the as-grown gallium sulfide crystals. Energy dispersive spectroscopy (EDS) analysis verified the stoichiometry of the Ga2S3 compound.
The experimental near band edge structure of Ga2S3 was characterized by thermoreflectance (TR), photoluminescence (PL) and transmittance measurements. The experimental results confirmed that Ga2S3 is a direct semiconductor, which show three band-edge transitions of A = 3.07 eV、B = 3.24 eV and C = 3.29 eV at room temperature. Polarized TR measurements revealed B and C transitions are polarization dependent. From optical measurements of polarized TR, PL and transmittance, we can confirm A, B and C transitions in Ga2S3 are originated from different origins. Besides, by PL measurements, many lower-energy transitions which can be attributed to be the defect-state transitions are observed. The temperature dependences of PL measurements at low temperatures also identify the emissions of bound exciton and free exciton transitions of Ga2S3.
On the basis of experimental results, the optical properties of monoclinic Ga2S3 have thus been realized.

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