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

THANK YOU FOR YOUR ATTENTION