Synthesis of Large-Area Tungsten Disulfide Films on Pre-Reduced Tungsten Suboxide Substrates.

We report a facile method for the synthesis of large-area tungsten disulfide (WS2) films by means of chemical vapor deposition (CVD). To promote WS2 film growth, the precursor solution, which includes pre-reduced tungsten suboxides, is prepared by using hydrazine as the strong reducing agent and spin-coated onto the growth substrate. Growth is then carried out in a CVD chamber vaporized with dimethyl disulfide as the sulfur precursor. Although only WS2 flakes are grown with unreduced tungsten precursors under a hydrogen atmosphere, WS2 films are readily attained on pre-reduced tungsten suboxide substrates without the need for further reduction by hydrogen, which is noted to induce discontinuity of the grown film. The result presents the coverage of WS2 to be proportional to the amount of reduced tungsten suboxides, which is revealed by X-ray photoelectron spectroscopy. Furthermore, it is found that the multilayer WS2 flakes grow along the grain boundary, which allows the analysis of the grain size of WS2 films by optical microscopy images only. WS2 field effect transistors are fabricated by conventional photolithography and show an average electron mobility of 0.4 cm2 V-1 s-1 and a high on/off ratio of 106 at room temperature.

[1]  S. Kim,et al.  Water-Assisted Synthesis of Molybdenum Disulfide Film with Single Organic Liquid Precursor , 2017, Scientific Reports.

[2]  S. Banerjee,et al.  Intra-domain periodic defects in monolayer MoS2 , 2017, 1705.03051.

[3]  David J. Singh,et al.  Valence Band Splitting on Multilayer MoS2: Mixing of Spin-Orbit Coupling and Interlayer Coupling. , 2016, The journal of physical chemistry letters.

[4]  Ting Yu,et al.  Electrically Tunable Valley-Light Emitting Diode (vLED) Based on CVD-Grown Monolayer WS2. , 2016, Nano letters.

[5]  B. Jonker,et al.  Synthesis of Large-Area WS2 monolayers with Exceptional Photoluminescence , 2015, Scientific Reports.

[6]  C. Li,et al.  Correction: Large-area synthesis of monolayer WS₂ and its ambient-sensitive photo-detecting performance. , 2015, Nanoscale.

[7]  S. De Gendt,et al.  Low temperature deposition of 2D WS2 layers from WF6 and H2S precursors: impact of reducing agents. , 2015, Chemical communications.

[8]  Lianmao Peng,et al.  Large-area synthesis of high-quality and uniform monolayer WS2 on reusable Au foils , 2015, Nature Communications.

[9]  M. Tanemura,et al.  Effect of WO3 precursor and sulfurization process on WS2 crystals growth by atmospheric pressure CVD , 2015 .

[10]  E. Yang,et al.  The growth scale and kinetics of WS2 monolayers under varying H2 concentration , 2015, Scientific Reports.

[11]  Zhongfan Liu,et al.  Chemical vapor deposition of monolayer WS2 nanosheets on Au foils toward direct application in hydrogen evolution , 2015, Nano Research.

[12]  Pinshane Y. Huang,et al.  High-mobility three-atom-thick semiconducting films with wafer-scale homogeneity , 2015, Nature.

[13]  J. Robertson,et al.  Chalcogen vacancies in monolayer transition metal dichalcogenides and Fermi level pinning at contacts , 2015 .

[14]  M. S. Jeong,et al.  Synthesis of centimeter-scale monolayer tungsten disulfide film on gold foils. , 2015, ACS nano.

[15]  Yanlong Wang,et al.  Thermal conductivity determination of suspended mono- and bilayer WS2 by Raman spectroscopy , 2015, Nano Research.

[16]  Chun Li,et al.  Large-area synthesis of monolayer WS₂ and its ambient-sensitive photo-detecting performance. , 2015, Nanoscale.

[17]  Yuan Wang,et al.  Monolayer excitonic laser , 2015, Nature Photonics.

[18]  B. Xiang,et al.  Controllable synthesis of high quality monolayer WS2 on a SiO2/Si substrate by chemical vapor deposition , 2015 .

[19]  A Gholinia,et al.  Light-emitting diodes by band-structure engineering in van der Waals heterostructures. , 2014, Nature materials.

[20]  G. Ozin,et al.  Colloidal synthesis of 1T-WS2 and 2H-WS2 nanosheets: applications for photocatalytic hydrogen evolution. , 2014, Journal of the American Chemical Society.

[21]  Satoru Suzuki,et al.  Scalable synthesis of layer-controlled WS2 and MoS2 sheets by sulfurization of thin metal films , 2014 .

[22]  Kenji Watanabe,et al.  Direct chemical vapor deposition growth of WS2 atomic layers on hexagonal boron nitride. , 2014, ACS nano.

[23]  J. Shan,et al.  Tightly bound excitons in monolayer WSe(2). , 2014, Physical review letters.

[24]  Xiaodong Cui,et al.  Exciton Binding Energy of Monolayer WS2 , 2014, Scientific Reports.

[25]  Aaron M. Jones,et al.  Electrically tunable excitonic light-emitting diodes based on monolayer WSe2 p-n junctions. , 2013, Nature nanotechnology.

[26]  John Robertson,et al.  Sulfur vacancies in monolayer MoS2 and its electrical contacts , 2013 .

[27]  Yu Zhang,et al.  Controlled growth of high-quality monolayer WS2 layers on sapphire and imaging its grain boundary. , 2013, ACS nano.

[28]  A. Neto,et al.  Strong Light-Matter Interactions in Heterostructures of Atomically Thin Films. , 2013 .

[29]  K. Novoselov,et al.  Strong Light-Matter Interactions in Heterostructures of Atomically Thin Films , 2013, Science.

[30]  Hua Zhang,et al.  The chemistry of two-dimensional layered transition metal dichalcogenide nanosheets. , 2013, Nature chemistry.

[31]  M. Dresselhaus,et al.  Synthesis and transfer of single-layer transition metal disulfides on diverse surfaces. , 2013, Nano letters.

[32]  Hui He,et al.  Thickness identification of two-dimensional materials by optical imaging , 2012, Nanotechnology.

[33]  H. Zeng,et al.  Optical signature of symmetry variations and spin-valley coupling in atomically thin tungsten dichalcogenides , 2012, Scientific Reports.

[34]  Hisato Yamaguchi,et al.  Coherent atomic and electronic heterostructures of single-layer MoS2. , 2012, ACS nano.

[35]  Wang Yao,et al.  Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides. , 2011, Physical review letters.

[36]  A. Radenović,et al.  Single-layer MoS2 transistors. , 2011, Nature nanotechnology.

[37]  G. Marin,et al.  Theoretical study of the thermal decomposition of dimethyl disulfide. , 2010, The journal of physical chemistry. A.

[38]  A. Splendiani,et al.  Emerging photoluminescence in monolayer MoS2. , 2010, Nano letters.

[39]  S. Banerjee,et al.  Large-Area Synthesis of High-Quality and Uniform Graphene Films on Copper Foils , 2009, Science.