Direct observation of the work function evolution of graphene-two-dimensional metal contacts

The work function evolution of a graphene monolayer under two-dimensional metal electrodes was studied by combining in situ metal deposition and ultraviolet photoelectron spectroscopy under an ultra-high vacuum system. The process of the charge transfer at the graphene–metal interfaces was investigated. The transfer of electrons from metal to graphene and then from graphene to metal, with deposition of the metal, was observed. The work function of the graphene–metal contact shifted, and was finally stopped at the theoretical work function of the metal when the metal turned from a two-dimensional film into a bulk material. Meanwhile, the energy barrier of the metal–graphene interface could be tailored by altering the metal thickness. This research makes it possible to use the graphene device in future applications.

[1]  J. Brink,et al.  First-principles study of the interaction and charge transfer between graphene and metals , 2009, 0902.1203.

[2]  W. Marsden.  I and J , 2012 .

[3]  N. Bartelt,et al.  Orientation-dependent work function of graphene on Pd(111) , 2010 .

[4]  Wi Hyoung Lee,et al.  Work-Function Engineering of Graphene Electrodes by Self-Assembled Monolayers for High-Performance Organic Field-Effect Transistors. , 2011, The journal of physical chemistry letters.

[5]  Seung-Hwan Lee,et al.  Plasma treatments to improve metal contacts in graphene field effect transistor , 2011 .

[6]  W. J. Liu,et al.  Understanding Asymmetric Transportation Behavior in Graphene Field-Effect Transistors Using Scanning Kelvin Probe Microscopy , 2011, IEEE Electron Device Letters.

[7]  A. Kahn,et al.  Energy level alignment at interfaces of organic semiconductor heterostructures , 1998 .

[8]  T. Ren,et al.  Graphene/semiconductor heterojunction solar cells with modulated antireflection and graphene work function , 2013 .

[9]  Andreas Stemmer,et al.  Variations in the work function of doped single- and few-layer graphene assessed by Kelvin probe force microscopy and density functional theory , 2011 .

[10]  E. Vogel,et al.  First-principles study of metal–graphene interfaces , 2010 .

[11]  S. Stankovich,et al.  Chemical analysis of graphene oxide films after heat and chemical treatments by X-ray photoelectron and Micro-Raman spectroscopy , 2009 .

[12]  T. Saitoh,et al.  Large enhancement of the effective lifetime of n-type multicrystalline silicon by two step spin-on phosphorus diffusion and SiO2 passivation , 2011 .

[13]  Y. Chabal,et al.  Metal-graphene-metal sandwich contacts for enhanced interface bonding and work function control. , 2012, ACS nano.

[14]  Kwang S. Kim,et al.  Tuning the graphene work function by electric field effect. , 2009, Nano letters.

[15]  Luigi Colombo,et al.  Large-area graphene single crystals grown by low-pressure chemical vapor deposition of methane on copper. , 2011, Journal of the American Chemical Society.

[16]  Kyeongjae Cho,et al.  Realistic metal-graphene contact structures. , 2014, ACS nano.

[17]  B. Kong,et al.  First-principles calculation of thermal transport in metal/graphene systems , 2013, 1303.6936.

[18]  M. Batzill,et al.  Graphene destruction by metal-carbide formation: An approach for patterning of metal-supported graphene , 2010 .

[19]  Shui-Tong Lee,et al.  Energy level alignment at Alq/metal interfaces , 1998 .

[20]  Robert M. Wallace,et al.  The effect of chemical residues on the physical and electrical properties of chemical vapor deposited graphene transferred to SiO2 , 2011 .

[21]  P. Lysaght,et al.  On chemical bonding and electronic structure of graphene–metal contacts , 2013 .

[22]  B. Hsieh,et al.  Work function of indium tin oxide transparent conductor measured by photoelectron spectroscopy , 1996 .

[23]  S. Yumitori.  Correlation of C1s chemical state intensities with the O1s intensity in the XPS analysis of anodically oxidized glass-like carbon samples , 2000 .

[24]  M. Yoshitake,et al.  A work function study of ultra-thin alumina formation on NiAl(1 1 0) surface , 2005 .

[25]  G. Barillaro,et al.  Light emission from silicon/gold nanoparticle systems , 2010 .