Post on 19-Jan-2016
S. A. Giamini
Graphene
A hexagonal honeycomb lattice of carbon. In its basic form it is a one-atom thick (2D) sheet.
Interesting properties:Better electric conductor than copper, high mobility, ballistic transport, great thermal conductivity, harder than diamond, almost completely transparent and more…
Dedkov et. al Epitaxial Graphene on Metals
Motivation
Grow graphene by CVD with Ni as catalyst
Understand and describe methods and techniques that could help graphene integration and application
Single layer Graphene - Good quality - Large area
• Thermal budget • Growth temperature
IC industry
Post-silicon era
Growth of graphene by CVD
Growth process
Growth chamber
Transfer process
Graphene on nickel foil 25 μm – Typical Growth at 600 °C
I2D/IG = 0.7 Fwhm = 65
• 3 layers or more• Low defects• Non uniform
| Copper foil side
| Nickel foil side
Deposition of copper on nickel foil in electrochemical cell
Deposition of amount equivalent to ~10 nm of copper(100)
12 2 22 HCONH H O 2[ (HCONH ) ] 2enCu n Cu
12 ( ) 22[ (HCONH ) ] +2e HCONHn sCu Cu n
Graphene (transferred) from nickel foil 25 μm –copper decorated Growth at 600 °C
I2D/IG > 3 Fwhm = 30ID/IG ~1 high
Growth over the entire surfaceUnconnected areas
Graphene Raman I2D/IG mapping and XPS spectra
C-sp2, 284.4 eV
C-sp3, 285.4 eV
C=O, ~287 eV
XPS shows well defined sp2 peakwith very little "contaminants"
Raman I2D/IG mapping shows good uniformity with ratio > 1.5
Graphene from nickel foil 25 μm – copper decorated Importance of surface roughness
I2D/IG > 3ID/IG ~ 0.15
Low defect – Single Layer Graphene
I2D/IG > 3ID/IG ~ 1
High defect – Single Layer Graphene
Graphene STM and lattice measurements
Line profiles in agreementwith theoretical values
STM showing the honeycomb lattice of graphene
Conclusions
Graphene growth by CVDNickel as the catalyst
Single layer growth on copper decorated nickelLow temperature process (600 °C)
Tune growth parameters for continuous mm-sized grapheneInvestigation of the role of copper during growth
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