Everything (?) you always wanted to know about GRAPHENE - …or

228 Pages·2012·13.25 MB·English

by  Marco Piazzi

Everything (?) you always wanted to know about
GRAPHENE
...or maybe not
Marco Piazzi
UniversitàdegliStudi-Turin&I.N.Ri.M.-Turin
February 15, 2012
default Introductionandmotivations
CVDgrowthofgrapheneonvariousmetalcatalysts
Conclusions
1 Introduction and motivations
Theoretical properties, Klein paradox, QHE
Experimental applications
2 CVD growth of graphene on various metal catalysts
CVD on Nickel
CVD on Copper and Iron
Graphene transfer and characterization - Raman Spectroscopy
3 Conclusions
M.Piazzi Everything(?)youalwayswantedtoknowaboutGRAPHENE
default Introductionandmotivations
CVDgrowthofgrapheneonvariousmetalcatalysts
Conclusions
Figure: Number of publications about graphene in past 20 years. Adapted
from Singh et al., Prog. in Mat. Science 56, 1178 (2011)
M.Piazzi Everything(?)youalwayswantedtoknowaboutGRAPHENE
default Introductionandmotivations
CVDgrowthofgrapheneonvariousmetalcatalysts
Conclusions
Figure: (left) Number of documents published yearly worldwide, on Carbon
Nanotubes and graphene, in past 8 years (according to database SCOPUS).
Adapted from Etxebarria et al., Scientometrics - online first articles (January
2012). (right) Number of publications on graphene in past 20 years. Adapted
from Singh et al., Prog. in Mat. Science 56, 1178 (2011)
M.Piazzi Everything(?)youalwayswantedtoknowaboutGRAPHENE
default Introductionandmotivations
Theoreticalproperties,Kleinparadox,QHE
CVDgrowthofgrapheneonvariousmetalcatalysts
Experimentalapplications
Conclusions
1 Introduction and motivations
Theoretical properties, Klein paradox, QHE
Experimental applications
2 CVD growth of graphene on various metal catalysts
CVD on Nickel
CVD on Copper and Iron
Graphene transfer and characterization - Raman Spectroscopy
3 Conclusions
M.Piazzi Everything(?)youalwayswantedtoknowaboutGRAPHENE
default Introductionandmotivations
Theoreticalproperties,Kleinparadox,QHE
CVDgrowthofgrapheneonvariousmetalcatalysts
Experimentalapplications
Conclusions
What is GRAPHENE? -
Basic Cristallography
Graphene: 2D hexagonal honeycumb lattice of Carbon atoms
m
ALWAYS equivalent to 2 interpenetrating triangular lattices
Figure: Graphene’s direct (left) and reciprocal (right) lattices. Adapted from
Castro Neto et al., Rev. Mod. Phys. 81, 109 (2009)
Graphene space-group: P6/mmm
M.Piazzi Everything(?)youalwayswantedtoknowaboutGRAPHENE
default Introductionandmotivations
Theoreticalproperties,Kleinparadox,QHE
CVDgrowthofgrapheneonvariousmetalcatalysts
Experimentalapplications
Conclusions
Crystallographic parameters
C - C distance δ = kδ k ’ 1.42 Å, ∀i = 1,...,3
i
√ (cid:16)√ (cid:17)
Real space primitive vectors a = 3δ 3,±1
1/2 2 √
Lattice constant ka k = ka k = 3δ ’ 2.46 Å
1 2
(cid:16) (cid:17)
Reciprocal space primitive vectors b = √2π √1 ,±1
1
/2 3δ 3
Reciprocal lattice constant kb k = kb k = 4π
1 2 3δ
Basis - direct primitive cell Two atoms: A and B
Basis - reciprocal primitive cell Dirac Points: K and K0
M.Piazzi Everything(?)youalwayswantedtoknowaboutGRAPHENE
default Introductionandmotivations
Theoreticalproperties,Kleinparadox,QHE
CVDgrowthofgrapheneonvariousmetalcatalysts
Experimentalapplications
Conclusions
What is GRAPHENE? -
The “missing” allotropic form of Carbon...
M.Piazzi Everything(?)youalwayswantedtoknowaboutGRAPHENE
default Introductionandmotivations
Theoreticalproperties,Kleinparadox,QHE
CVDgrowthofgrapheneonvariousmetalcatalysts
Experimentalapplications
Conclusions
... and the “seed” for the other allotropic forms
M.Piazzi Everything(?)youalwayswantedtoknowaboutGRAPHENE
astonishing transport properties: very high charge carriers mo-
bility µ (up to 2·105cm2V−1s−1 in the free-standing case), high
Fermi velocity v ’ c/300 ’ 106m/s, an Ambipolar Electric
F
Field Effect at GhZ frequencies;
a real possibility to be used in future Nanoelectronics devices
(transistors, spin valves, etc.), but also in many other applica-
tions (touch screens, hydrogen storage, bio-sensors)
default Introductionandmotivations
Theoreticalproperties,Kleinparadox,QHE
CVDgrowthofgrapheneonvariousmetalcatalysts
Experimentalapplications
Conclusions
Why graphene?
Graphene is a truly 2D system and it’s possible to grow it as free-
standing or on an insulating substrate. As such, it presents:
new interesting theoretical properties for a condensed matter
system: linear dispersion relation at low energies, charge trans-
portduetomasslessDirac-likefermions,evidenceofKleinpara-
dox, a robust Anomalous Integer and Fractional QHE (even ar
room temperature);
M.Piazzi Everything(?)youalwayswantedtoknowaboutGRAPHENE