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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/30431

Title: 層狀單晶二硫化鉬摻雜金與銀之光學特性研究
The Study of Optical Properties on gold and silver doped Molybdenum Disulphide Layered Single Crystals
Authors: Loo-Jack Liu
Contributors: NTOU:Department of Electrical Engineering
Keywords: 二硫化鉬;拉曼散射;壓電調製反射光譜;電解液電場調製反射光譜
Molybdenum Disulphide;Raman scattering;PzR;EER
Date: 2011
Issue Date: 2011-11-25T07:45:08Z
Abstract: 層狀單晶半導體二硫化鉬(MoS2)屬於過渡性金屬雙硫屬化合物(transition-metal-dichalcogenides)簡稱 TMDCs。層內原子鍵結屬於部分共價鍵與離子鍵混合型式,而層與層之間僅有微弱的凡得瓦爾力(van der waals force)。 本論文是使用化學氣相傳導法(chemical vapor transport method)以溴為傳導劑成長MoS2,另外在成長MoS2中,分別加入金(Au)與銀(Ag),對這三種樣品進行研究。藉由X光繞射技術(XRD)可以發現摻雜金和銀的晶體結構並無改變;利用附在場發射式掃描式電子顯微鏡上的能量散佈分析儀(EDS)來確認其加入元素的訊號;以兩種不同雷射為激發源的拉曼散射光譜(Raman scattering spectra)可以得到一階拉曼散射模態E12g(383 cm-1)和A1g(408 cm-1)以及幾個二階拉曼模態。吸收量測實驗結果可判定其為間接能隙,而摻雜金和銀的間接能隙會有紅移現象。 在調製光譜部分,使用壓電(PzR)和電解液電場(EER)兩種調製技術去找出樣品激子躍遷的訊號及其展寬外,並對溫度與激子躍遷和展寬變化的關係加以討論。
In this work, Au-doped and Ag-doped MoS2 single crystals have been grown by chemical vapor transport method using bromine as the transporting agent. By analyzing the X-ray diffraction patterns, the structure of the doped MoS2 remains the 2H-polytypic symmetry as that of the undoped one. Energy dispersive X-ray spectroscopy (EDS) has been employed to determine the contents of the dopants for the doped MoS2 samples. A considerable discrepancy exists between the nominal doping contents and those determined by EDS. Raman scattering spectra reveal the two dominant first-order Raman–active modes, E12g(383 cm-1) and A1g(408 cm-1), and several second-order modes. The results of optical absorption measurements indicate that both of the Au-doped and Ag-doped MoS2 are indirect semiconductors. The obtained indirect energy gaps show red shifts with dopants of Au and Ag. The effects of dopants on the direct band-edge excitonic transitions are studied by using the electrolyte electroreflectance (EER) and piezoreflectance (PzR) measurements at room temperature. In addition, the temperature dependence of near band-edge excitonic transitions of the samples has been studied by PzR measurements in the temperature range of 25 to 300 K. From a detailed lineshape fit of the PzR spectra, the energies and broadening parameters of the A and B excitons are determined accurately. The parameters that describe the temperature variation of the energies and broadening function of the near band-edge excitonic transitions are evaluated and discussed.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M98530083
Appears in Collections:[電機工程學系] 博碩士論文

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