二硫化钼,二维材料性质ppt课件

二硫化钼，二硫化钨、二硫化钛、二硒化钼
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TMDCs的奇特性质
The presence of unsaturated d-orbitals contributed by transition metals to the material's band structure introduces a multitude of interesting properties
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II. Introduce fabrication method of the 2D materials
Exfoliation:
“Scotch tape method”
Chemical exfoliation
For example : ion intercalation
The ion intercalation method uses the concept of ion insertion in the gaps between the MoS2 layers, widening the layer gaps
Growth:
Grown from precursors Grown by CVD
For example : precursor consisted of thin layer of molybdenum 在衬底（此处是蓝宝石）上蒸镀一层单质Mo，然后在高温（~1000°C）硫氛围 下进行硫化反应
I. Discuss the interesting property of fewlayered MoS2 materials
II. Introduce fabrication method of the 2D materials and analyze their advantage and the disadvantage
materials.
新技术，仪器的应用：
二维材料制备方法
新原子物理理论：
原子厚度层级理论
新种二维材料：
TMDCs（过渡金属硫化物） 拓扑绝缘体
各种二维材料结构示意图
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什么是TMDCs ？
TMDCs are MX2-type compounds where M is a transition element from groups IV, V, and VI of the periodic table and X represents the chalcogen species S, Se, and Te.
1. charge density waves 2. Magnetism 3. superconductivity 4. band gaps vary with the number of
layers
MoS2 :因为其在自然中易得性和实用性，是目前 TMDCs中研究最广泛的二维材料
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CONTEND
缺点是采用的电化学方法，可能 会改变材料的性质（2H态和1T 态），对于反应条件的要求比较 苛刻
Illustration of controlled lithiation and Subseq exfoliation using an electrochemical setup
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II. Introduce fabrication method of the 2D materials
随层数减少，MoS2的带隙类 型由间接带隙变为直接带隙 这使得其在光学探测领域具 有潜力
4lay 6 3lay
2lay
1lay
I. Discuss the interesting property of fewlayered MoS2 materials
能带工程
垂直电场 A vertical electric field exerted to few-layer MoS2 is found to be an efficient method for band gap engineering. The band gap of bilayer MoS2 could be tuned to zero with an electric field of about 1.0-1.5 V/Å. 拉伸应变 Band structure redesign under tensile strain is predicted to lower the electron effective mass and consequently improve electrfabrication method of the 2D materials
Exfoliation:
“Scotch tape method” Chemical exfoliation
Exfoliation of MoS2.(a)Optical and(b)AFM height image of multilayer sections of a MoS2 flake on a 285nm silicon oxide substrate.
III. Highlight the current application of fewlayered MoS2 materials.
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I. Discuss the interesting property of fewlayerd MoS2 materials
带隙类型随层数变化
Hybridization between p z-orbitals of S atoms and the d-orbitals of molybdenum atoms and are affected by interlayer interactions. The bands at Γ are more affected by a decrease in layer number
Few-Layer MoS2: A Promising Layered Semiconductor
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THE PREFACE
The single-layer graphene opened up new possibilities and research into the physics of two-dimensional