Direct measurement of the thickness-dependent electronic band structure of MoS2 using angle-resolved photoemission spectroscopy.

We report on the evolution of the thickness-dependent electronic band structure of the two-dimensional layered-dichalcogenide molybdenum disulfide (MoS2). Micrometer-scale angle-resolved photoemission spectroscopy of mechanically exfoliated and chemical-vapor-deposition-grown crystals provides direct evidence for the shifting of the valence band maximum from Γ to K, for the case of MoS2 having more than one layer, to the case of single-layer MoS2, as predicted by density functional theory. This evolution of the electronic structure from bulk to few-layer to monolayer MoS2 had earlier been predicted to arise from quantum confinement. Furthermore, one of the consequences of this progression in the electronic structure is the dramatic increase in the hole effective mass, in going from bulk to monolayer MoS2 at its Brillouin zone center, which is known as the cause for the decreased carrier mobility of the monolayer form compared to that of bulk MoS2.

[1]  E. Sutter,et al.  Microscopy of Graphene Growth, Processing, and Properties , 2013 .

[2]  Timothy C. Berkelbach,et al.  Grains and grain boundaries in highly crystalline monolayer molybdenum disulphide. , 2013, Nature materials.

[3]  P. Avouris,et al.  Electroluminescence in single layer MoS2. , 2012, Nano letters.

[4]  K. Menon,et al.  Inhomogeneous band bending on MoS2(0001) arising from surface steps and dislocations , 2012, Journal of physics. Condensed matter : an Institute of Physics journal.

[5]  Keliang He,et al.  Control of valley polarization in monolayer MoS2 by optical helicity. , 2012, Nature nanotechnology.

[6]  Z. Yin,et al.  Single-layer MoS2 phototransistors. , 2012, ACS nano.

[7]  Tao Qian,et al.  A precise method for visualizing dispersive features in image plots. , 2011, The Review of scientific instruments.

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

[9]  Changgu Lee,et al.  Anomalous lattice vibrations of single- and few-layer MoS2. , 2010, ACS nano.

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

[11]  Stefan Goedecker,et al.  ABINIT: First-principles approach to material and nanosystem properties , 2009, Comput. Phys. Commun..

[12]  M. Hybertsen,et al.  Electronic structure of few-layer epitaxial graphene on Ru(0001). , 2009, Nano letters.

[13]  J. Flege,et al.  A new soft X-ray photoemission microscopy beamline at the National Synchrotron Light Source , 2007 .

[14]  Michael S. Fuhrer,et al.  Realization and electrical characterization of ultrathin crystals of layered transition-metal dichalcogenides , 2007 .

[15]  Xavier Gonze,et al.  A brief introduction to the ABINIT software package , 2005 .

[16]  K. Novoselov,et al.  Two-dimensional atomic crystals. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[17]  R. B. Murray,et al.  The band structures of some transition metal dichalcogenides. III. Group VIA: trigonal prism materials , 1972 .

[18]  J. Wilson,et al.  The transition metal dichalcogenides discussion and interpretation of the observed optical, electrical and structural properties , 1969 .