Two dimensional WS2 lateral heterojunctions by strain modulation

“Strain engineering” has been widely used to tailor the physical properties of layered materials, like graphene, black phosphorus, and transition-metal dichalcogenides. Here, we exploit thermal strain engineering to construct two dimensional (2D) WS2 in-plane heterojunctions. Kelvin probe force microscopy is used to investigate the surface potentials and work functions of few-layer WS2 flakes, which are grown on SiO2/Si substrates by chemical vapor deposition, followed by a fast cooling process. In the interior regions of strained WS2 flakes, work functions are found to be much larger than that of the unstrained regions. The difference in work functions, together with the variation of band gaps, endows the formation of heterojunctions in the boundaries between inner and outer domains of WS2 flakes. This result reveals that the existence of strain offers a unique opportunity to modulate the electronic properties of 2D materials and construct 2D lateral heterojunctions.

[1]  Soo Ho Choi,et al.  Layer-number-dependent work function of MoS2 nanoflakes , 2014 .

[2]  Jianbin Xu,et al.  Lateral Built‐In Potential of Monolayer MoS2–WS2 In‐Plane Heterostructures by a Shortcut Growth Strategy , 2015, Advanced materials.

[3]  Kuan-Hua Huang,et al.  Synthesis of lateral heterostructures of semiconducting atomic layers. , 2015, Nano letters.

[4]  Jun Lou,et al.  Vertical and in-plane heterostructures from WS2/MoS2 monolayers. , 2014, Nature materials.

[5]  Klaus von Klitzing,et al.  Four-terminal magneto-transport in graphene p-n junctions created by spatially selective doping. , 2009, Nano letters.

[6]  Jed I. Ziegler,et al.  Bandgap engineering of strained monolayer and bilayer MoS2. , 2013, Nano letters.

[7]  Yong-Wei Zhang,et al.  Quasiparticle band structures and optical properties of strained monolayer MoS 2 and WS 2 , 2012, 1211.5653.

[8]  W. Ge,et al.  Tuning the graphene work function by uniaxial strain , 2015 .

[9]  Christian Kloc,et al.  Lattice dynamics in mono- and few-layer sheets of WS2 and WSe2. , 2013, Nanoscale.

[10]  P. L. McEuen,et al.  The valley Hall effect in MoS2 transistors , 2014, Science.

[11]  Tobin J Marks,et al.  Hybrid, Gate-Tunable, van der Waals p-n Heterojunctions from Pentacene and MoS2. , 2016, Nano letters.

[12]  Investigation of band-offsets at monolayer-multilayer MoS₂ junctions by scanning photocurrent microscopy. , 2015, Nano letters.

[13]  Tobin J. Marks,et al.  Gate-tunable carbon nanotube–MoS2 heterojunction p-n diode , 2013, Proceedings of the National Academy of Sciences.

[14]  E. Johnston-Halperin,et al.  Progress, challenges, and opportunities in two-dimensional materials beyond graphene. , 2013, ACS nano.

[15]  Zheng Liu,et al.  Two-dimensional heterostructures: fabrication, characterization, and application. , 2014, Nanoscale.

[16]  A. Kis,et al.  Piezoresistivity and Strain-induced Band Gap Tuning in Atomically Thin MoS2. , 2015, Nano letters.

[17]  Jer-Lai Kuo,et al.  Orbital analysis of electronic structure and phonon dispersion in MoS 2 , MoSe 2 , WS 2 , and WSe 2 monolayers under strain , 2013 .

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

[19]  Yugui Yao,et al.  Effect of doping and strain modulations on electron transport in monolayer MoS 2 , 2014 .

[20]  Burke,et al.  Generalized Gradient Approximation Made Simple. , 1996, Physical review letters.

[21]  R. Arita,et al.  Valley-dependent spin polarization in bulk MoS2 with broken inversion symmetry. , 2014, Nature nanotechnology.

[22]  Eun Sung Kim,et al.  Synthesis of Large‐Area Graphene Layers on Poly‐Nickel Substrate by Chemical Vapor Deposition: Wrinkle Formation , 2009 .

[23]  H. Schmidt,et al.  Electronic transport properties of transition metal dichalcogenide field-effect devices: surface and interface effects. , 2015, Chemical Society reviews.

[24]  Martin L Dunn,et al.  Ultrastrong adhesion of graphene membranes. , 2011, Nature nanotechnology.

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

[26]  Soon Cheol Hong,et al.  Thickness and strain effects on electronic structures of transition metal dichalcogenides: 2H- M X 2 semiconductors ( M = Mo, W; X = S, Se, Te) , 2012 .

[27]  Hierarchy of graphene wrinkles induced by thermal strain engineering , 2013, 1306.0171.

[28]  Zhong Lin Wang,et al.  Piezoelectricity of single-atomic-layer MoS2 for energy conversion and piezotronics , 2014, Nature.

[29]  Yi Cui,et al.  Physical and chemical tuning of two-dimensional transition metal dichalcogenides. , 2015, Chemical Society reviews.

[30]  Kai Yan,et al.  Modulation-doped growth of mosaic graphene with single-crystalline p–n junctions for efficient photocurrent generation , 2012, Nature Communications.

[31]  Challa S. S. R. Kumar,et al.  Surface Science Tools for Nanomaterials Characterization , 2015 .

[32]  L. Lauhon,et al.  Emerging device applications for semiconducting two-dimensional transition metal dichalcogenides. , 2014, ACS nano.

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

[34]  Yu Huang,et al.  Lateral epitaxial growth of two-dimensional layered semiconductor heterojunctions. , 2014, Nature nanotechnology.

[35]  Yingchun Ding,et al.  Thermal expansion tensors, Gruneisen parameters and phonon velocities of bulk MT2 (M = W and Mo; T = S and Se) from first principles calculations , 2015 .

[36]  J. Johns,et al.  Seed Crystal Homogeneity Controls Lateral and Vertical Heteroepitaxy of Monolayer MoS2 and WS2. , 2015, Journal of the American Chemical Society.

[37]  Yan Peng Liu,et al.  Quantum mechanical rippling of a MoS2 monolayer controlled by interlayer bilayer coupling. , 2015, Physical review letters.

[38]  Effects of mismatch strain and substrate surface corrugation on morphology of supported monolayer graphene , 2010, 1003.0853.

[39]  Yan Li,et al.  Strain induced piezoelectric effect in black phosphorus and MoS2 van der Waals heterostructure , 2015, Scientific Reports.

[40]  B. Mehta,et al.  Nanoscale Mapping of Layer-Dependent Surface Potential and Junction Properties of CVD-Grown MoS2 Domains , 2015 .

[41]  Jean-Christophe Charlier,et al.  Identification of individual and few layers of WS2 using Raman Spectroscopy , 2013, Scientific Reports.

[42]  Jr-hau He,et al.  Epitaxial growth of a monolayer WSe2-MoS2 lateral p-n junction with an atomically sharp interface , 2015, Science.

[43]  Wang Yao,et al.  Lateral heterojunctions within monolayer MoSe2-WSe2 semiconductors. , 2014, Nature materials.

[44]  Xiaohui Qiu,et al.  Quasi-freestanding monolayer heterostructure of graphene and hexagonal boron nitride on Ir(111) with a zigzag boundary. , 2014, Nano letters.