direct writing of conductive regions in graphene oxide … irradiation & patterning direct...

FIB Irradiation & Patterning


Direct Writing of Conductive Regions in Graphene Oxide via Focused Ion Beam (FIB) Irradiation

By: Derrek E. Lobo, Monash University, Victoria, Australia Supervisor: Dr Mainak Majumder



Motivation

Patterning of graphitic materials

FIB irradiation as a reduction method for graphene oxide

Planar capacitors

Current progress



Motivation Background FIB Exposure Planar Capacitors Current Progress

• Good material stability and strength • High electronic mobility hence high conductivity

• Spatial patterning opens up many applications in nano-electronics

• Specifically the fabrication of planar microsupercapacitors

A. K. Geim, K. S. Novoselov, The rise of graphene. Nat Mater 6, 183 (2007). Ohta, T.; Bostwick, A.; Seyller, T.; Horn, K.; Rotenberg, E. Controlling the electronic structure of bilayer graphene. Science 2006, 313, 951−954. Son, Y.; Cohen, M. L.; Louie, S. G. Energy gaps in graphene nanoribbons. Phys. Rev. Lett. 2006, 97, 216803.




• Mechanical exfoliation

• Wet chemical synthesis

• Epitaxial growth

• Chemical vapour deposition (CVD)

• Arc discharge




Westervelt, R.M., Graphene Nanoelectronics. Science, 2008. 320(5874): p. 324-325.

Bell, D.C., et al., Precision cutting and patterning of graphene with helium ions. Nanotechnology, 2009. 20(45): p. 455301.

Dimiev, A., et al., Layer-by-Layer Removal of Graphene for Device Patterning. Science, 2011. 331(6021): p. 1168-1172.




Wang, Q.H. and M.C. Hersam, Characterization and nanopatterning of organically functionalized graphene with ultrahigh vacuum scanning tunneling microscopy. MRS Bulletin, 2011. 36(07): p. 532-542.

Byun, I.-S., et al., Nanoscale Lithography on Monolayer Graphene Using Hydrogenation and Oxidation. ACS Nano, 2011. 5(8): p. 6417-6424.




Graphene oxide is made up of a sp2 bonded carbon lattice work with oxygen functionalities attached. These functionalities give it interesting chemical properties with the possibility of grafting additional groups to them. Reduction of GO leads to interesting electrical properties as well (GO is insulating while rGO is conductive) in fact it is 5 orders of magnitude more conductive than GO.

Gao, W., et al., New insights into the structure and reduction of graphite oxide. Nat Chem, 2009. 1(5): p. 403-408. Stankovich, S., et al., Synthesis of graphene-based nanosheets via chemical reduction of exfoliated graphite oxide. Carbon, 2007. 45(7): p. 1558-1565. Zhu, Y., et al., Graphene and Graphene Oxide: Synthesis, Properties, and Applications. Advanced Materials, 2010. 22(35): p. 3906-3924.




Wei, Z., et al., Nanoscale Tunable Reduction of Graphene Oxide for Graphene Electronics. Science, 2010. 328(5984): p. 1373-1376.

Y. Zhang et al., Direct imprinting of microcircuits on graphene oxides film by femtosecond laser reduction. Nano Today 5, 15 (2010).




Benefits : Small feature size Tuneable amount of reduction Complex patterning possible Hypothesis(conservation of momentum) Ga ions are incident on the GO substrate with a certain amount of momentum this leads to deformation on the c-c and c-o bonding structure. Since the c-o bonding is weaker these are more likely to be effected and broken leading to a reduction of the GO substrate.




D. E. Lobo, J. Fu, T. Gengenbach, M. Majumder, Localized Deoxygenation and Direct Patterning of Graphene Oxide Films by Focused Ion Beams. Langmuir 28, 14815 (2012/10/16, 2012).




Specific capacitance: 2.50 mF/cm2

Energy density: 9.03 x 10-7 Wh/cm2

Power density: 3.57 x 10-3 W/cm2

Electrolyte: 1M Na2SO4

Gao, W., et al. (2011). "Direct laser writing of micro-supercapacitors on hydrated graphite oxide films." Nat Nano 6(8): 496-500.




Specific capacitance: 2.32 mF/cm2

Energy density: 1.60 x 10-6 Wh/cm2

Power density: 1.07 x 10-1 W/cm2

Ionic liquid: 1-butyl-3-methylimidazolium bis(trifluoromethylsulfony)imide with fumed silica nanopowder

El-Kady, M. F. and R. B. Kaner (2013). "Scalable fabrication of high-power graphene micro-supercapacitors for flexible and on-chip energy storage." Nat Commun 4: 1475.




• We provide a novel way to directly pattern rGO regions on a GO film.

• There exists two clear regimes one of preferential reduction and one of preferential amorphisation.

• The feature sizes can range from 15nm to 100µm.

• Shows good potential as a method for the fabrication of all carbon planar capacitors.

Summary




Acknowledgements Dr Mainak Majumder Dr Jing Fu Dr Thomas Gengenbach My Lab mates Parama Banerjeea, Phillip Sheath, Rachel Tkacz, Sam Martin and Mahdokht Emadishaibani




Thank you

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