The XIII-th International School-Conference
The Actual Problems of Microworld Physics
Gomel, Belarus, July 27 - August 7, 2015
Electromagnetic properties
of graphene films and their
applications
K.Batrakov, P.Kuzhir, S.Maksimenko, V.Saroka, S.Voronovich, N. Valynets, A.
Paddubskaya
1. Some interest facts about some graphene structures;
2. Brief review of ideas and achievements in the field of
graphene based applications;
3. Our investigations and proposals: theory and
experiments;
4. Conclusion
Graphene
Graphene, a 2-dimensional flat monolayer of carbon atoms arranged in a honeycomb
lattice, is a promising candidate to be the basic building material for nanoscale
electronic applications. Due to the hexagonal lattice structure of graphene, an interesting
and elegant electronic structure arises, namely that of a gapless semi-metal with a linear
dispersion relation in the vicinity of the Fermi level at the K-points in the Brillouin zone.
Graphene was discovered experimentally in 2004
K.S. Novoselov et al., Science 306, 666 (2004).
Some interesting facts about graphene
1) Massless Dirac electrons
2) Klein tunneling.
Experimental confirmation of the Klein tunnelling:
Stander, Huard &Goldhaber-Gordon, 2009; Young & Kim, 2009
Macroscopically large mean free path (16 micron)
Walt A. de Heer Exceptional ballistic transport in epitaxial graphene nanoribbons
Nature 2014 doi:10.1038/nature12952
These two features reveal possibility of more simple operation of graphene electrons by
electric and magnetic fields!!!
Quantum Hall and other quantum effects
Novoselov et. al. Nature, 2005
Very high room-temperature electron mobility 2.5 x 105 cm2V-1 s-1 and possibility to increase mobility
to the value 2 x 106 cm²·V−1·s−1
Ability to sustain extremely high densities of electric current (a million times
higher than copper)
Moser, J., Barreiro, A. & Bachtold, A. Appl. Phys. Lett. 91, 163513 (2007).
Optical absorption of exactly πα≈2.3%
Nair, R. R. et al. Fine structure constant defines visual transparency of graphene. Science 320, 1308 (2008).
Walt A de Heer, Exceptional ballistic transport in epitaxial graphene nanoribbons Nature (2014)
10.1038/nature12952
(p,0) zigzag nanoribbons;
(p,1) armchair nanoribbons.
FIG. a) A typical structure of nanoribbons. A solid circle stands for a carbon atom with one electron,
while an open circle for a different atom such as a hydrogen. A closed area represents a unit cell. It is
possible to regard the lattice made of solid circles as a part of a honeycomb lattice. b) A nanoribbon
is constructed from
a chain of m connected carbon hexagons, as depicted in dark gray, and by translating this chain by
the translational vector T=qa+b, q<m. A nanoribbon
is indexed by a set of two integers (p,q) with p=m−q.
Motohiko Ezawa PHYSICAL REVIEW B 73, 045432 2006.
• Plasmon amplification
A.Bostwick, T. Ohta, T. Seyller, Karsten Horn, E. Rotenberg, Nature, 3, 36, (2007);
Rana F. Graphene terahertz plasmon oscillators. IEEE Trans. NanoTechnol. 7, 91–99 (2008)
O. V. Kibis, M. Rosenau da Costa, M. E. Portnoi, Generation of Terahertz Radiation by Hot Electrons in
Carbon Nanotubes NanoLetters, 7 (11), 3414, (2006).
Experimental observation Taiichi Otsuji1, Hiromi Karasawa1, Tsuneyoshi Komori1, Takayuki Watanabe and
Victor Ryzhii 2010.
Taiichi Otsuji “Recent advances in the research toward graphene-based terahertz lasers”
Proc. of SPIE Vol. 9382, 938219 · © 2015 SPIE · CCC code: 0277-786X/15/$18 · doi: 10.1117/12.2079411
Electron-hole injection
• Harmonic generation, Rabi oscillations and Rabi-waves
H. K. Avetissian, G. F. Mkrtchian, K. G. Batrakov, S. A. Maksimenko, and A. Hoffmann
Phys. Rev. B 88, 245411 (2013)
H. K. Avetissian, G. F. Mkrtchian, K. G. Batrakov, S. A. Maksimenko, and A. Hoffmann,
Phys. Rev. B 88, 165411 (2013 )
Harmonic emission rate at the multiphoton excitation in bilayer graphene for
different parameters χ:(a) χ=0.2, (b) χ=0.3,(c) χ=0.4,(d) χ=0.5, ω=1 meV.
Ubitron-type generator
If a fast electron moves in a periodic potential
, its momentum
and velocity oscillates in time with the frequency
The frequency of radiation
can be tuned in these devices by varying the accelerating voltage which determines the
electron.
S. A. Mikhailov, Graphene-based voltage-tunable coherent terahertz emitter. Phys. Rev. B 87,
115405 (2013).
Dispersion law in graphene
Graphene stripes
• Cherenkov-type emissions in nanotubes and graphene
K. G. Batrakov, P. P. Kuzhir, S. A. Maksimenko, Proc.SPIE 6328, 63280Z (2006).
K. G. Batrakov, P. P. Kuzhir, and S. A. Maksimenko, Physica E 40, 1065 2008).
K. G. Batrakov, P. P. Kuzhir, and S. A. Maksimenko, Physica E 40, 2370 (2008).
K.G. Batrakov, O.V. Kibis, Polina P. Kuzhir, M. R. Costa, and M. E. Portnoi, Terahertz processes
in carbon nanotubes. Journal of Nanophotonics, Vol. 4, 041665 (2010).
K.G. Batrakov, P. P. Kuzhir, S. A. Maksimenko, Physica B: Condensed Matter, 405 3050 (2010).
K. G. Batrakov, P. P. Kuzhir, S. A. Maksimenko and C. Tomsen, Carbon nanotube as a Cherenkovtype light emitter and free electron laser Phys. Rev. B 79, 125408 (2009).
K. Batrakov, V. Saroka, S. Maksimenko, Ch. Thomsen Plasmon polariton deceleration in graphene
structures. Nanophoton. 6(1), 061719 (Dec 05, 2012). doi:10.1117/1.JNP.6.061719
1) Very large current density (up to 1010 A/cm2 ) [M. Radosavljevi´c,
J. Lefebvre, and A. T. Johnson, “High-field electrical transport and breakdown in
bundles of single-wall carbon nanotubes”, Phys. Rev. B 64, 241 307® (2001);
S.-B. Lee, K. B. K. Teo, L. A. W. Robinson, A. S. Teh, M. Chhowalla,
et al., J. Vac. Sci. Technol. B 20, 2773 (2002)];
2) Ballistic electron transport (up to 10 μm ) [C. Berger, P. Poncharal, Y. Yi,
W. A. de Heer,Ballistic Conduction in Multiwalled Carbon Nanotubes,
J. Nanosci. Nanotechn., 3, 171 (2003)];
3) The strong electromagnetic wave slowing down [G. Ya. Slepyan, S. A. Maksimenko,
A. Lakhtakia, O. Yevtushenko, A. V. Gusakov, Phys. Rev. B 60, 17136 (1999)].
V. A. Saroka, K. G. Batrakov, and L. A. Chernozatonskii Edge Modified Zigzag-Shaped Graphene
Nanoribbons: Structure and Electronic Properties. Physics of the Solid State, 2014, Vol. 56, No. 10, pp.
2135–2145
V A Saroka, K G Batrakov, V A Demin and L A Chernozatonskii Band gaps in jagged and straight
graphene nanoribbons tunable by an external electric field J. Phys.: Condens. Matter 27 (2015) 145305
doi:10.1088/0953-8984/27/14/145305
Microwave probing in Ka-band (26-37.5 GHz)
The EM response of samples as ratios of transmitted/input (S21) and reflected/input (S11) signals was
measured within the 26-37 GHz frequency range (Ka-band).
The waveguide cross-section was 7.2×3.4 mm.
Scalar analyzer R2-408R(VSWR and Transmission Loss
Meter R2-408R)
H. Bosman, Y. Y. Lau, and R. M. Gilgenbach, Appl. Phys. Lett., Vol. 82, No. 9
Pyrolytic carbon (PyC), 5-240 nm thick
V. G. Andreev, V. A. Vdovin, and P. S. Voronov, Tech. Phys. Lett. 29(11), 953 (2003). on silica substrate (0.5 mm)
Transmission and absorption in ultra-thing pyrolytic films
waveguide
free space
There is optimal film thickness!
Multi-layered graphene films: catalytic CVD process

0.5 mm quartz sample was coated with copper thin film which was physically deposited, i.e. by thermal evaporation in
vacuum (10-5 mBar) condition, on the quartz surface.

The used copper layer thickness was 300 nm which is thick enough for surviving of dewetting in high temperature
without making holes but thin enough for carbon atoms to get through grain boundaries.

Before the process, the CVD chamber was cleansed with nitrogen (twice) and hydrogen to remove oxygen remains from
the chamber.

Next the Cu coated quartz sample was heated in hydrogen atmosphere (7 mBar) to 700 °C.

At this temperature hydrogen was pumped from the chamber and methane-hydrogen gas mixture (1:1) was injected in
the chamber until the pressure was ~10 mBar.

The temperature was then risen to 950 °C with rate of 10 °C/min.

After 5 min the chamber was cooled down to 700 °C during 60 min and the CH4-H2 atmosphere was replaced with
hydrogen (7 mBar).

After the CVD process, the remaining Cu was removed by ferric chloride (FeCl3) solution and rinsed with water.
Transfer and deposition of several graphene layers
According to Raman spectrum investigations,
monolayer graphene is 90-95% of monolayers
and 10-5% of bilayer graphene.
PMMA -poly(methyl methacrylate) is
a transparent thermoplastic
According to Raman spectrum investigations,
monolayer graphene is 90-95% of monolayers
and 10-5% of bilayer graphene.
Dependence of absorption on graphene layers
numbers n for “silica+graphene” geometry
Dependence of absorption on graphene layers
numbers n for “graphene+silica” geometry
Absorption depending on number
of graphene monolayers in two
different geometries
Enhancing absorption due to “substrate effect”
Substrate thickness at which absorption in graphene is increased
Graphene surface conductivity must satisfy to condition
Additional possibility to increase absorption in graphene due to choice of substrate
value of maximal absorption:
Absorption in graphene without substrate:
In free space (without waveguide)
Зависимость поглощения от толщины дополнительного слоя эпоксидной смолы
Absorption
1
0.7
2
0.6
3
0.5
4
0.4
5
0.3
6
7
0.00
0.05
0.10
0.15
0.20
0.25
0.30
Thickness
Transmission of terahertz radiation through free standing graphene: one graphene layer
(top curve) and three sandwich layers (bottom curve) :
Transmission
0.8
0.6
0.4
0.2
0.2
0.4
0.6
0.8
1.0
1.2
THz
Dependence of absorption in graphene on wave incidence:
The main results:
• Ballistic electron dynamics at large in graphene-like structures leads to possibility of stimulated
radiation and developing of terahertz emitters based on these structures
• Simple electrostatic emission frequency tuning.
• Large absorption of electromagnetic radiation is very important property for using in high sensible
detectors
Acknowledgments
БРФФИ № Ф06Р-101,
БРФФИ № Ф08Р-009 ,
БРФФИ № Ф11АРМ-006,
EU FP7 TerACan project FP7-230778,
BMBF(Germany) project BLR 08/001,
EU FP7 CACOMEL project FP7-247007,
EU FP7 BY-NanoERA project FP7-266529, Call ID FP7-INCO-2010-6, 2010-2013
EU FP7 644076 CA-RISE “Collective Excitations in Advanced Nanostructures (CoExAN)” From 201510-01 to 2019-10-01,
EU FP7 604391 Graphene Flagship “Multi-layered sandwich graphene devices (MILESAGE)”
.
THANK YOU FOR ATTENTION