1、Few-Layer MoS2: A Promising Layered SemiconductorTHE PREFACEThe single-layer graphene opened up new possibilities and research into the physics of two-dimensional materials. 新技術，儀器的應用： 二維材料制備方法新原子物理理論：原子厚度層級理論新種二維材料：TMDCs（過渡金屬硫化物）拓撲絕緣體各種二維材料結構示意圖什么是？TMDCs are MX2-type compounds where M is a transiti

2、on element from groups IV, V, and VI of the periodic table and X represents the chalcogen species S, Se, and Te.二硫化鉬，二硫化鎢、二硫化鈦、二硒化鉬 The presence of unsaturated d-orbitals contributed by transition metals to the materials band structure introduces a multitude of interesting properties的奇特性質1.charge de

3、nsity waves2.Magnetism3.superconductivity4.band gaps vary with the number of layersMoS2 :因為其在自然中易得性和實用性，是目前TMDCs中研究最廣泛的二維材料CONTENDI.Discuss the interesting property of few-layered MoS2 materialsII. Introduce fabrication method of the 2D materials and analyze their advantage and the disadvantageIII.

4、Highlight the current application of few-layered MoS2 materials.I. I.Discuss the interesting property of few-Discuss the interesting property of few-layerdlayerd MoS2 materials MoS2 materials帶隙類型隨層數變化4lay 3lay 2lay 4lay 3lay 2lay 1lay1layHybridization between p z-orbitals of S atoms and the d-orbita

5、ls of molybdenum atoms and are affected by interlayer interactions. The bands at are more affected by a decrease in layer number隨層數減少，MoS2的帶隙類型由間接帶隙變為直接帶隙這使得其在光學探測領域具有潛力I. I.Discuss the interesting property of Discuss the interesting property of few-few-layered layered MoS2 materialsMoS2 materials能帶

6、工程垂直電場A vertical electric field exerted to few-layer MoS2 is found to be an efficientmethod for band gap engineering. The band gap of bilayer MoS2 could be be tuned to zero tuned to zero with an electric field of about 1.0-1.5 V/.拉伸應變Band structure redesign under tensile strain is predicted to lower

7、 the electron effective mass and consequently improve electron mobilityII. Introduce II. Introduce fabrication method of the fabrication method of the 2D2D materials materialsExfoliation:“Scotch tape method” Chemical exfoliationExfoliation of MoS2.(a)Optical and(b)AFM height image of multilayer sect

8、ions of a MoS2 flake on a 285nm silicon oxide substrate.II. Introduce fabrication method of the 2DII. Introduce fabrication method of the 2D materials materialsExfoliation:“Scotch tape method” Chemical exfoliationIllustration of controlled lithiation and Subsequent exfoliation using an electrochemic

9、al setupFor example For example : ion : ion intercalationintercalationThe ion intercalation method uses the concept of ion insertion in the gaps between the MoS2 layers, widening the layer gaps缺點是采用的電化學方法，可能會改變材料的性質（2H態和1T態），對于反應條件的要求比較苛刻For example : precursor consisted For example : precursor cons

10、isted of thin of thin layer of layer of molybdenummolybdenum在襯底（此處是藍寶石）上蒸鍍一層單質Mo，然后在高溫（1000C）硫氛圍下進行硫化反應產物性質產物性質grain sizes：10-30nm，field-effect mobility between 10 and 14 cm2/Vs相對于物理剝離法，仍有較大差距（ Mob ：400cm2/Vs）Growth:Grown from precursorsGrown by CVDII. Introduce fabrication method of the 2DII. Intro

11、duce fabrication method of the 2D materials materialsIII. Highlight the current application of few-layered MoS2 materials.少層二硫化鉬因其出眾的物理和電學性質，已經在場效應管，異質結器件，電路器件，光電器件，傳感器等領域都有報道。MoS2和石墨烯的異質結結構制成的快閃存儲單元，利用了石墨烯的高電子遷移率和MoS2有帶隙的特點，其存儲電荷能夠保存30%在十年內。采用High-k電介質材料，高質量襯底制備出高電子遷移率的FET器件200 to 400 cm2/VsIII. Hi

12、ghlight 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

13、MoS2幾種單層MoS2材料制成的光電探測器APPLICATIONWhile 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.NanoribbonsNanoribbons（納米帶）：MoS2 nanoribbons are basically very thin nanosized strips having widths much smaller than their lengthsNanotu