Controlling Grain Size and Continuous Layer Growth in Two-Dimensional MoS2 Films for Nanoelectronic Device Application

We report that control over the grain size and lateral growth of monolayer MoS<sub>2</sub> film, yielding a uniform large-area monolayer MoS<sub>2</sub> film, can be achieved by submitting the SiO<sub>2</sub> surfaces of the substrates to oxygen plasma treatment and modulating substrate temperature in chemical vapor deposition (CVD) process. Scanning electron microscopy and atomic force microscopy images and Raman spectra revealed that the MoS<sub>2</sub> lateral growth could be controlled by the surface treatment conditions and process temperatures. Moreover, the obtained monolayer MoS<sub>2</sub> films showed excellent scalable uniformity covering a centimeter-scale SiO<sub>2</sub> /Si substrates, which was confirmed with Raman and photoluminescence mapping studies. Transmission electron microscopy measurements revealed that the MoS<sub>2</sub> film of the monolayer was largely single crystalline in nature. Back-gate field effect transistors based on a CVD-grown uniform monolayer MoS<sub>2</sub> film showed a good current on/off ratio of ~10<sup>6</sup> and a field effect mobility of 7.23 cm<sup>2</sup>/V·s. Our new approach to growing MoS<sub>2</sub> films is anticipated to advance studies of MoS<sub>2</sub> or other transition metal dichalcogenide material growth mechanisms and to facilitate the mass production of uniform high-quality MoS<sub>2</sub> films for the commercialization of a variety of applications.

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

[2]  Yu-Chuan Lin,et al.  Growth of large-area and highly crystalline MoS2 thin layers on insulating substrates. , 2012, Nano letters.

[3]  Satyaprakash Sahoo,et al.  Temperature-Dependent Raman Studies and Thermal Conductivity of Few-Layer MoS2 , 2013 .

[4]  Jannik C. Meyer,et al.  The structure of suspended graphene sheets , 2007, Nature.

[5]  Jing Kong,et al.  Role of the seeding promoter in MoS2 growth by chemical vapor deposition. , 2014, Nano letters.

[6]  Lain‐Jong Li,et al.  Synthesis of Large‐Area MoS2 Atomic Layers with Chemical Vapor Deposition , 2012, Advanced materials.

[7]  Il-Kwon Oh,et al.  Synthesis of wafer-scale uniform molybdenum disulfide films with control over the layer number using a gas phase sulfur precursor. , 2014, Nanoscale.

[8]  Shin-Shem Pei,et al.  High mobility and high on/off ratio field-effect transistors based on chemical vapor deposited single-crystal MoS2 grains , 2013 .

[9]  Ya Dong Li,et al.  Formation of MoS2 inorganic fullerenes (IFs) by the reaction of MoO3 nanobelts and S. , 2003, Chemistry.

[10]  S. Dey,et al.  Optical and vibrational studies of partially edge-terminated vertically aligned nanocrystalline MoS2 thin films , 2013 .

[11]  Yi Liu,et al.  Controlled Scalable Synthesis of Uniform, High-Quality Monolayer and Few-layer MoS2 Films , 2013, Scientific Reports.

[12]  Liying Jiao,et al.  Controlled synthesis of highly crystalline MoS2 flakes by chemical vapor deposition. , 2013, Journal of the American Chemical Society.

[13]  Jun Lou,et al.  Vapour phase growth and grain boundary structure of molybdenum disulphide atomic layers. , 2013, Nature materials.

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

[15]  Yihong Wu,et al.  Annealing and oxidation of silicon oxide films prepared by plasma-enhanced chemical vapor deposition , 2005 .

[16]  N. Lee,et al.  Charge inhomogeneity of graphene on SiO2: dispersion-corrected density functional theory study on the effect of reactive surface sites , 2014 .

[17]  Xiaodong Xu,et al.  Vapor-solid growth of high optical quality MoS₂ monolayers with near-unity valley polarization. , 2013, ACS nano.

[18]  Qing Hua Wang,et al.  Electronics and optoelectronics of two-dimensional transition metal dichalcogenides. , 2012, Nature nanotechnology.

[19]  Can Ataca,et al.  Stable, Single-Layer MX2 Transition-Metal Oxides and Dichalcogenides in a Honeycomb-Like Structure , 2012 .

[20]  P. Ajayan,et al.  Large Area Vapor Phase Growth and Characterization of MoS2 Atomic Layers on SiO2 Substrate , 2011, 1111.5072.

[21]  S. Sahoo,et al.  Surface energy engineering for tunable wettability through controlled synthesis of MoS2. , 2014, Nano letters.

[22]  E. Seebauer,et al.  Estimating surface diffusion coefficients , 1995 .

[23]  Yu-Chuan Lin,et al.  Wafer-scale MoS2 thin layers prepared by MoO3 sulfurization. , 2012, Nanoscale.

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

[25]  J. Shan,et al.  Atomically thin MoS₂: a new direct-gap semiconductor. , 2010, Physical review letters.

[26]  Boris I. Yakobson,et al.  Vapor Phase Growth and Grain Boundary Structure of Molybdenum Disulfide Atomic Layers , 2013 .

[27]  Yu Zhang,et al.  Epitaxial monolayer MoS2 on mica with novel photoluminescence. , 2013, Nano letters.

[28]  Hugen Yan,et al.  Anomalous lattice vibrations of single- and few-layer MoS2. , 2010, ACS nano.