二硫化钼,二维材料性质

III.
Highlight the current application of few-layered MoS2 materials.
少层二硫化钼因其出众的物理和 电学性质，已经在场效应管，异 质结器件，电路器件，光电器件， 传感器等领域都有报道。
采用High-k电介质材料，高质量 衬底制备出高电子迁移率的FET 器件200 to∼400 cm2/Vs
二硫化钼，二硫化钨、二硫化钛、二硒化钼
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
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
产物性质 grain sizes：10-30nm，field-effect mobility between 10 and 14 cm2/Vs 相对于物理剥离法，仍有较大差距（ Mob ：400cm2/Vs）
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
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.
Illustration of controlled lithiation and Subsequent exfoliation using an electrochemical setup
II.
Introduce fabrication method of the 2D materials

Growth:
Nanoribbons（纳米带）：MoS2 nanoribbons are basically very thin nanosized strips having widths much smaller than their lengths Nanotubes(MNT)：MoS2 Nanotubes are nanosized tube-liked single-layered MoS2 materials
III. Highlight the current application of fewlayered MoS2 materials.
I.
wenku.baidu.com
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 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
1. 2. charge density waves Magnetism
3.
4.
superconductivity
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
CONTEND
I. Discuss the interesting property of fewlayered MoS2 materials II. Introduce fabrication method of the 2D materials and analyze their advantage and the disadvantage
Illustrations of (a) zigzag and (b) armchair MoS2 nanoribbons.
(d) zigzag and (e) armchair MoS2 nanotubes.
水准有限，请各位老师和学长指正！
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 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
MoS2和石墨烯的异质结结构制成的快闪存 储单元，利用了石墨烯的高电子迁移率和 MoS2有带隙的特点，其存储电荷能够保存 30%在十年内。
III.
Highlight the current application of few-layered MoS2 materials.
The direct transition optical gap in few-layer MoS2 opens the doors to interesting optoelectronic applications. The very first MoS2 optoelectronic device was reported by Yin et al. The device was a phototransistor fabricated on monolayer MoS2
II.

Introduce fabrication 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.
Few-Layer MoS2: A Promising Layered Semiconductor
THE PREFACE
The single-layer graphene opened up new possibilities and research into the physics of two-dimensional materials.
几种单层MoS2材料制成的光电探测器
APPLICATION
While huge research interests are focused on 2D MoS2 sheets, other nanostructures like MoS2 nanotubes and Nano ribbons have received attention for their confinement-induced physics and properties.
4lay
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 electron mobility