Effects of particle contamination and substrate interaction on the Raman response of unintentionally doped graphene

We investigated the inhomogeneities in the charge density of unintentionally doped graphene on SiO2 prepared by mechanical exfoliation. From the analysis of the G, D, and 2D phonon modes of the Raman spectra after displacing contaminants on graphene surface, and measuring the separation monolayer-substrate distance among zones with different doping levels, we deduce that the interaction with the substrate is the main cause of doping in graphene rather than particle contamination. In particular, we show how graphene doping levels vary within the same flake depending on the distance between graphene and the substrate.

[1]  K. Klitzing,et al.  Observation of electron–hole puddles in graphene using a scanning single-electron transistor , 2007, 0705.2180.

[2]  E. Williams,et al.  Atomic structure of graphene on SiO2. , 2007, Nano letters.

[3]  K. Novoselov,et al.  Raman Fingerprint of Charged Impurities in Graphene , 2007, 0709.2566.

[4]  Lei Liu,et al.  Probing charged impurities in suspended graphene using Raman spectroscopy. , 2009, ACS nano.

[5]  Zhao Zhang,et al.  Substrate-regulated morphology of graphene , 2010 .

[6]  E. Williams,et al.  Charged Impurity Scattering in Graphene , 2007, 0708.2408.

[7]  SUPARNA DUTTASINHA,et al.  Graphene: Status and Prospects , 2009, Science.

[8]  J. Coleman,et al.  High-yield production of graphene by liquid-phase exfoliation of graphite. , 2008, Nature nanotechnology.

[9]  N. Marzari,et al.  Uniaxial Strain in Graphene by Raman Spectroscopy: G peak splitting, Gruneisen Parameters and Sample Orientation , 2008, 0812.1538.

[10]  F. Guinea,et al.  The electronic properties of graphene , 2007, Reviews of Modern Physics.

[11]  Stéphane Berciaud,et al.  Probing the intrinsic properties of exfoliated graphene: Raman spectroscopy of free-standing monolayers. , 2009, Nano letters.

[12]  Peng Chen,et al.  Effective doping of single-layer graphene from underlying SiO2 substrates , 2009 .

[13]  K. Kamaras,et al.  Anomalies in thickness measurements of graphene and few layer graphite crystals by tapping mode atomic force microscopy , 2008, 0812.0690.

[14]  F. Guinea,et al.  Electrostatic interactions between graphene layers and their environment , 2007, 0712.2232.

[15]  Michael F. Crommie,et al.  Origin of spatial charge inhomogeneity in graphene , 2009, 0902.4793.

[16]  L. Samuelson,et al.  Controlled manipulation of nanoparticles with an atomic force microscope , 1995 .

[17]  J. Heath,et al.  Scanning tunneling microscopy characterization of the electrical properties of wrinkles in exfoliated graphene monolayers. , 2009, Nano letters.

[18]  W. Wegscheider,et al.  Morphology and flexibility of graphene and few-layer graphene on various substrates , 2008, 0806.4074.

[19]  A Gupta,et al.  Raman scattering from high-frequency phonons in supported n-graphene layer films. , 2006, Nano letters.

[20]  C. N. Lau,et al.  Temperature dependence of the Raman spectra of graphene and graphene multilayers. , 2007, Nano letters.

[21]  H. R. Krishnamurthy,et al.  Monitoring dopants by Raman scattering in an electrochemically top-gated graphene transistor. , 2008, Nature nanotechnology.

[22]  M. Lazzeri,et al.  Nonadiabatic Kohn anomaly in a doped graphene monolayer. , 2006, Physical review letters.

[23]  A. Ferrari,et al.  Raman spectroscopy of graphene and graphite: Disorder, electron phonon coupling, doping and nonadiabatic effects , 2007 .

[24]  Andre K. Geim,et al.  Raman spectrum of graphene and graphene layers. , 2006, Physical review letters.

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

[26]  S. Sarma,et al.  Measurement of scattering rate and minimum conductivity in graphene. , 2007, Physical review letters.

[27]  Cinzia Casiraghi,et al.  Probing disorder and charged impurities in graphene by Raman spectroscopy , 2009 .

[28]  S. Roth,et al.  Effects of charge impurities and laser energy on Raman spectra of graphene. , 2008, Nano letters.

[29]  K. Novoselov,et al.  Rayleigh imaging of graphene and graphene layers. , 2007, Nano letters.

[30]  K. Novoselov,et al.  Breakdown of the adiabatic Born-Oppenheimer approximation in graphene. , 2007, Nature materials.

[31]  K. Novoselov,et al.  Raman spectroscopy of graphene edges. , 2008, Nano letters.

[32]  Andre K. Geim,et al.  Electric Field Effect in Atomically Thin Carbon Films , 2004, Science.