本論文使用化學氣相傳導法( Chemical Vapor Transport，CVT）並以碘作為傳導劑成長鉻摻雜之二硒化鉬 (Mo1-xCrxSe2，x=0, 0.01, 0.05, 0.1, 0.2) 系列層狀單晶半導體與三硒化二鉻Cr2Se3單晶塊材。Mo1-xCrxSe2為層狀單晶半導體且屬於過渡性金屬硫屬化合物 (Transition-Metal-Dichalcogenides) 簡稱 TMDCs，過渡性金屬硫屬化合物在近年來引起了廣大的注意，主因是它們對於新一代電子或光電元件具有相當大的應用潛力，且長期被研究於光電與能源應用材料。
本論文將利用掃瞄式電子顯微鏡(Scanning Electron Microscopy， SEM)與能量散佈光譜儀 (Energy Dispersive Spectrometer，EDS)及X射線光電子能譜儀 (X-Ray Photoelectron Spectroscopy，XPS) 確認晶體的成分比例與晶體中原子與原子之間的化學鍵結構；經由X-Ray晶格繞射分析儀 (X-Ray Diffraction，XRD) 分析Mo1-xCrxSe2與Cr2Se3系列之結構維持於六方體結構，且當鉻摻雜於二硒化鉬時晶格常數a與c會隨著鉻成份增加而變大；在穿透式電子顯微鏡(Transmission Electron Microscope，TEM )中可觀察晶體結晶品質，以固態532nm雷射為激發源量測拉曼散射光譜 (Raman Scattering Spectra) 可得到一階拉曼模態E1g 與A1g且隨著鉻成份增加而往低波速位移。
光電學量測實驗，藉由光穿透光譜( Photo Transmission，Tr )與光電導光譜(Photo Conductivity，PC)實驗及熱調制光譜(Thermoreflectance，TR)實驗，分別對樣品進行實驗，可觀測Mo1-xCrxSe2系列在光穿透與光電導實驗中，近能隙的躍遷訊號，在熱調制光譜(Thermoreflectance，TR)實驗，可觀測Mo1-xCrxSe2系列的激子躍遷訊號EA1、EA2、EB隨著鉻的成份變化產生紅移現象，Cr2Se3晶體在四點電阻率量測中，可以發現Cr2Se3隨溫度變化電阻率，呈現金屬特性，Mo1-xCrxSe2系列在熱探針實驗中，可觀測到樣品呈現n型半導體特性。光化學量測，由光催化降解實驗中，我們可以發現Mo1-xCrxSe2系列有非常好的光降解特性，隨鉻成份增加降解能力越好，因鉻內含Cr3+/Cr6+而Mo1-xCrxSe2以Cr6+為主，Cr6+助於光催化降解實驗中的降解速度，光催化降解實驗可應用在綠能產業。

In recent years, transition metal di chalcogenides (TMDCs) has received more attentions as potential materials for application as optoelectronic devices, green catalyst, hydrogen energy and also in solar cells. We have synthesized and grown the layered single crystals of chromium doped molybdenum di selenides Mo1-xCrxSe2 (0≤ x ≤0.2) series and also Cr2Se3 crystal using chemical vapor transport (CVT) method using Iodine as transport agent. Crystal structures of Mo1-xCrxSe2 series and Cr2Se3 are well identified by XRD measurement. An enhanced crystal quality and enlarged lattice constant of Mo1-xCrxSe2 series as a result of gradual increase of chromium amount were characterized by high resolution transmission electron microscope (HRTEM).
The first order E1g and A1g modes of these sample crystals were clearly detected by Raman spectroscopy which allowed shift to lower wavenumber as the chromium concentration increased in the series. Investigation on the various optical and photochemical properties such as photo-transmission, photoconductivity on both samples were carried out. The results showed good optical responsivity due to incorporation of chromium in the Mo1-xCrxSe2. The free excitonic features EA1, EA2 and EB of the chromium doped Mo1-xCrxSe2 were observed by thermoreflectance (TR) spectroscopy.
Metallic behavior of Cr2Se3 crystal was confirmed by four-point resistivity measurement, where the resistivity increases with temperature increased between 20 and 300K. Mo1-xCrxSe2 series displayed n-type semiconductor behavior by hot probe method owing to Cr6+. Thus, Mo1-xCrxSe2 explicated photo-catalyst nature of these sample crystals showed better degradation of methylene blue (MB) because of redox property of Cr3+/Cr6+ and reduced band gap of Mo1-xCrxSe2. Therefore, the tunable photo-catalyst nature of Mo1-xCrxSe2 series renders the material a suitable candidate for green energy application.

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