CVD-graphene on silicon was irradiated by accelerated heavy ions (Xe, 160 MeV, fluence of 1011 cm-2)
and characterized by Raman spectroscopy. The defectiveness of pristine graphene was found to be dominated
by grain boundaries while after irradiation it was determined by both grain boundaries and vacancies.
Respectively, average inter-defect distance decreased from ~ 24 to ~ 13 nm. Calculations showed that
the ion irradiation resulted in a decrease in charge carrier mobility from ~ 4.0 × 103 to ~ 1.3·103 cm2/V s.
The results of the present study can be used to control graphene structure, especially vacancies concentration,
and charge carrier mobility

Apel, P. Yu.

Kolesov, E. A.

Koltunowicz, T. N.

Komissarov, I. V.

Korolik, O. V.

Saad, A. M.

Skuratov, V. A.

Swic, A.

Tivanov, M. S.

Żukowski, P. V.

Комиссаров, И. В.

Kolesov, E.A.

Tivanov, M.S.

Korolik, O.V.

Apel, P.Yu.

Skuratov, V.A.

Saad, A.M.

Komissarov, I.V.

Żukowski, P.V.

Koltunowicz, T.N.

SocioEconomic Challenges Journal (Sumy State University)

JOURNAL OF NANO- AND ELECTRONIC PHYSICS ЖУРНАЛ НАНО- ТА ЕЛЕКТРОННОЇ ФІЗИКИ 
Vol. 9 No 3, 03020(4pp) (2017) Том 9 № 3, 03020(4cc) (2017) 
 
 
2077-6772/2017/9(3)03020(4) 03020-1  2017 Sumy State University 
Raman Study of CVD Graphene Irradiated by Swift Heavy Ions 
 
E.A. Kolesov1, M.S. Tivanov1,*, O.V. Korolik1, P. Yu. Apel2,3, V.A. Skuratov2,3,4, A.M. Saad5, 
I.V. Komissarov6, A. Swic7, P.V. Żukowski8, T.N. Koltunowicz8,† 
 
1 Belarusian State University, 4, Nezavisimosti Ave., 220030 Minsk, Belarus 
2 Joint Institute for Nuclear Research, 6, Joliot-Curie, 141980 Dubna, Russia 
3 Dubna State University, 141980 Dubna, Russia 
4 National Research Nuclear University MEPhI, Moscow, Russia 
5 Al-Balqa Applied University, PO Box 4545, 11953 Amman,  Jordan  
6 Belarusian State University of Informatics and Radioelectronics, 6, P. Brovka Str., 220013 Minsk, Belarus 
7 Institute of Technological Systems of Information, Lublin University of Technology, 20-618 Lublin, Poland 
8 Department of Electrical Devices and High Voltage Technology, Lublin University of Technology, 20-618 Lublin, 
Poland 
 
(Received 28 Febriary 2017; revised manuscript received 19 March 2017; published online 30 June 2017) 
 
CVD-graphene on silicon was irradiated by accelerated heavy ions (Xe, 160 MeV, fluence of 1011 cm-2) 
and characterized by Raman spectroscopy. The defectiveness of pristine graphene was found to be domi-
nated by grain boundaries while after irradiation it was determined by both grain boundaries and vacan-
cies. Respectively, average inter-defect distance decreased from  ~ 24 to ~ 13 nm. Calculations showed that 
the ion irradiation resulted in a decrease in charge carrier mobility from ~ 4.0 × 103 to ~ 1.3·103 cm2/V s. 
The results of the present study can be used to control graphene structure, especially vacancies concen-
tration, and charge carrier mobility. 
 
Keywords: Irradiated graphene, Defects, Raman spectroscopy, CVD, Swift heavy ions. 
 
DOI: 10.21272/jnep.9(3).03020 PACS numbers: 81.05.ue, 61.48.Gh, 
78.30.Ly, 61.80. – x 
 
 
                                                        
* tivanov@bsu.by 
† t.koltunowicz@pollub.pl 
1. INTRODUCTION 
 
Graphene is a promising material for a variety of 
applications. It is a two-dimensional sp2-carbon 
allotrope [1]. The importance of graphene studies is 
driven by its unique physical properties: optical 
transparency, high values of rigidity, thermal and 
electrical conductivity [2]. At present, graphene is used 
in transparent electrodes, field effect transistors, 
biosensors, etc. 
For several applications, graphene structure 
modification using controlled defect introduction is 
needed [3]. Swift heavy ions (SHI) irradiation method 
is a versatile and convenient tool for this purpose [4]. It 
allows one to create defects using a wide ion energy 
range, different fluences for obtaining different defect 
densities, and various ion types. However, the 
mechanism of defect formation in SHI-irradiated 
graphene is still unclear. 
Raman spectroscopy is a versatile tool for obtaining 
information on structural properties of various 
materials. This method is particularly useful in the 
context of graphene studies, due to monoatomic 
thickness of the material [1, 2]. As shown in [5], it is 
possible to determine the average inter-defect distance 
in laser spot area for graphene from D and G peaks 
maximum intensity ratio. Moreover, the correlation 
presented in [6] allows one to estimate graphene charge 
carrier mobility from the full width at half-maximum 
(FWHM) of 2D peak. 
Purpose of the present work is to study structural 
properties of SHI-irradiated graphene using Raman 
spectroscopy in order to understand how defect-caused 
structural changes influence graphene physical 
properties. 
 
2. EXPERIMENTAL 
 
Graphene studied in this paper was obtained by 
atmospheric pressure chemical vapor deposition (CVD). 
Prior to the synthesis, copper substrate was 
electrochemically polished in 1 M phosphoric acid 
solution for 5 min with operating voltage of 2.3 V. 
Synthesis was performed in a tubular quartz reactor 
with a diameter of 14 mm. Copper foil was pre-
annealed at 1050°C for 60 min under the following gas 
flow rates: hydrogen 150 cc/min, nitrogen 100 cc/min. 
Synthesis was performed under the following 
conditions: reactor temperature 1050 °C, C10H22 flow 
rate 4 μl/min, H2 flow rate 60 cc/min, N2 carrier flow 
rate 100 cc/min, synthesis time 30 min. After the 
hydrocarbon flow termination, the sample was cooled 
down to room temperature at a rate of ~ 50 C/min. 
Graphene was transferred to Si/SiO2 substrate by 
wet-chemical room-temperature etching without 
polymer support in two steps. First, one side of copper 
foil was treated for 3 min in a solution of H2NO3 and 
H2O mixed in a volume ratio of 1:3. Then the copper foil 
was totally dissolved in a water solution of FeCl3. 
Graphene film was washed several times in a bath with 
distilled water prior to being placed onto the substrate. 
Graphene was irradiated by 160 MeV xenon ions 
with total fluence of 1011 cm – 2 at the IC100 cyclotron 
at the FLNR JINR in Dubna [7]. Ion beam homogeneity 
 E.A. KOLESOV, M.S. TIVANOV, O.V. KOROLIK ET AL. J. NANO- ELECTRON. PHYS. 9, 03020 (2017) 
 
 
03020-2 
over the irradiated specimen surface was controlled 
using beam scanning in the horizontal and vertical 
directions and was better than 5 %. 
Raman spectra were obtained with a spectral 
resolution not less than 3 cm – 1 using a confocal Raman 
spectrometer Nanofinder HE (LOTIS TII). For 
excitation of Raman radiation, a continuous wave solid-
state laser with a wavelength of 473 nm was used. 
Room-temperature Raman measurements were carried 
out using laser power of 800 µW, the diameter of laser 
spot on the sample surface being about 0.6 µm. 
 
3. RESULTS AND DISCUSSION 
 
Typical Raman spectra for graphene before and 
after SHI irradiation are presented in Fig. 1. The 
presence of single-layer graphene in both cases is 
indicated by I2D/IG peak intensity ratios together with 
2D peak FWHMs and single Lorentzian 
approximations (insets in Fig. 1) [2, 8]. 
 
1200 1500 1800 2100 2400 2700
D'
2500 2600 2700 2800 2900
In
te
n
si
ty
, 
ar
b
. 
u
n
.
Raman Shift, cm
-1
FWHM = 44 cm
-1
2500 2600 2700 2800 2900
In
te
n
si
ty
, 
ar
b
. 
u
n
.
Raman Shift, cm
-1
FWHM = 38 cm
-1
In
te
n
si
ty
, 
ar
b
. 
u
n
.
Raman Shift, cm
-1
D
G
2D
 
 
Fig. 1 – Typical Raman spectra for graphene before (top) and after (bottom) ion irradiation. Insets:  2D peak approximations with 
single Lorentz functions 
 
As seen from the figure, D peak in pristine 
graphene spectrum has relatively low intensity 
(ID/IG ~ 0.3), which corresponds to a low defectiveness 
of the sample structure [1, 2]. A different situation is 
observed for irradiated graphene: typical Raman 
spectra in this case demonstrate ID/IG intensity ratios 
not less than ~ 0.5. However, in several areas ID/IG 
values up to of ~ 1.0 are observed. Based on this fact, 
we can conclude that graphene defectiveness increased 
after irradiation. 
According to [5], the average inter-defect distance in 
the laser spot area LD can be calculated from the ratio 
of D and G peak maximum intensities using the 
following expression: 
 
 
13
2 2
4 4
4.3 10 ( )
( )
( )( )
D
L
I D
L nm
I GE eV

  
  
 
, (3.1) 
 
where EL is an excitation energy. 
It is important to note that since the ID/IG ratio does 
not depend on a defect geometry [9], LD values 
calculated from the formula represent the average 
inter-defect distance for all Raman active defects that 
are involved in elastic scattering (since the process 
leading to D peak arising includes inelastic electron-
phonon scattering and elastic electron-defect scattering 
events [2]). 
The calculation results were averaged over all 
obtained spectra (400 spectra for each sample). For 
pristine graphene, the obtained inter-defect distance 
value was ~ 24 nm. The calculation has shown that 
after the irradiation the LD value decreased to ~ 13 nm, 
signifying the increased number of defects. At the same 
time, calculated average distance between the ions 
fallen onto graphene surface is ~ 16 nm. 
In order to obtain detailed information on defect 
distribution over graphene surface before and after the 
irradiation, Raman mappings across the surface were 
performed. Fig. 2 presents LD maps for graphene both 
before and after the irradiation. 
As seen from Fig. 2, the distribution of LD is regular 
over all scanned area both for pristine and irradiated 
graphene. The inter-defect distance uniformly 
decreased (and therefore the defect density increased) 
after the irradiation. 
In [9] it was shown that graphene defect type can be 
obtained from ID/ID’ intensity ratio. D’ peak for 
graphene is usually partially overlapped with G peak 
leading to combined asymmetric shape, as can be 
observed in Fig. 1, but its intensity can be easily 
obtained by simple deconvolution. Typical spectra of 
pristine graphene demonstrate ID/ID’ values of 1.0 - 3.5 
corresponding to grain boundaries. At the same time, 
irradiated graphene spectroscopy data shows 
ID/ID’ ~ 3.9 - 5.7. According to presented in [9] 
dependencies, these values indicate presence of both 
grain boundaries and vacancies. 
Fig. 3 shows Raman maps of the ID/ID’ intensity 
ratio giving the distribution of defect types over the 
scanned area. 
 RAMAN STUDY OF CVD GRAPHENE IRRADIATED BY SWIFT HEAVY IONS J. NANO- ELECTRON. PHYS. 9, 03020 (2017) 
 
 
03020-3 
 
 
 
 
Fig. 2 – Raman maps (20 × 20 m) of the average inter-defect 
distance for pristine (top) and irradiated (bottom) graphene; 
scanning step of 1 m 
 
It is seen from the figure that scanned pristine 
graphene area is dominated by grain boundaries. In 
turn, irradiated graphene map contains a large number 
of vacancies besides the boundaries. Moreover, Raman 
maps of LD and ID/ID’ for irradiated graphene show 
a very strong correlation, giving almost identical values 
distribution. This fact indicates that nearly all defects 
in this case are represented by vacancies induced 
during the irradiation. 
According to [6], charge carrier mobility μ in 
graphene can be determined from 2D peak full width at 
half-maximum (FWHM). The authors of [6] used 
combined Hall effect measurements and Raman 
spectroscopy. This method resulted in finding strong 
correlation between Hall mobility and 2D peak FWHM. 
Determination performed according to dependencies 
described in [6] gave the value of charge carrier 
mobility in pristine graphene averaged over all 400 
scanned spectra pr ~ 4.0·103 cm2/V s. For irradiated 
graphene, the average μirr was about 1.3·103 cm2/V s. 
The charge carrier mobility decrease after the 
irradiation can be explained by intensifying of charge 
carriers scattering by defects induced. 
 
4. CONCLUSION 
 
Raman studies of CVD-graphene on silicon substrate 
 
 
 
 
Fig. 3 – Raman maps (20 × 20 m) of the ID/ID’ intensity ratio 
for pristine (top) and irradiated (bottom) graphene; scanning 
step of 1 m. Types of defects corresponding to specific ID/ID’  
values are indicated under the scale 
 
substrate irradiated by accelerated heavy ions (Xe, 
160 Me V, fluence 1011 cm – 2) have shown the uniform 
distribution of defect types and inter-defect distances 
over graphene surface. The defectiveness of pristine 
graphene was dominated by grain boundaries while 
after irradiation it became determined by both grain 
boundaries and vacancies. The average inter-defect 
distance was found to decrease from ~ 24 to ~ 13 nm. 
Charge carrier mobilities in graphene before and after 
the ion irradiation were calculated. It was found that 
the irradiation resulted in a decrease of charge carrier 
mobility from ~ 4.0·103 to ~ 1.3·103 cm2/V s. The results 
of the present study can be used to control graphene 
structure, especially vacancies concentration, and 
charge carrier mobility. 
 
AKNOWLEDGEMENTS 
 
This work was partly supported by the statute tasks 
of the Lublin University of Technology, at the Faculty 
of Electrical Engineering and Computer Science,  
(S-28/E/2017), entitled “Researches of electrical, 
magnetic, thermal and mechanical properties of 
modern electrotechnical and electronic materials, 
 
 E.A. KOLESOV, M.S. TIVANOV, O.V. KOROLIK ET AL. J. NANO- ELECTRON. PHYS. 9, 03020 (2017) 
 
 
03020-4 
including nanomaterials and electrical devices and 
their components, in order to determination of 
suitability for use in electrical engineering and to 
increase the efficiency of energy management”. 
 
 
REFERENCES 
 
1. A.C. Ferrari, J.C. Meyer, V. Scardaci, C. Casiraghi, 
M. Lazzeri, F. Mauri, S. Piscanec, D. Jiang, 
K.S. Novoselov, S. Roth, A.K. Geim, Phys. Rev. Lett. 97, 
187401 (2006).  
2. A.C. Ferrari, D.M. Basko, Nature Nanotech. 8, 235 (2013).  
3. A.K. Geim, Science 324, 1530 (2009).  
4. J. Zeng, H.J. Yao, S.X. Zhang, P.F. Zhai, J.L. Duan, 
Y.M. Sun, G.P. Li, J. Liu, Nucl. Instr. Meth. Phys. Res. B 
330, 18 (2014).  
5. L.G. Cançado, A. Jorio, E.H. Martins Ferreira, F. Stavale, 
C.A. Achete, R.B. Capaz, M.V.O. Moutinho, A. Lombardo, 
T.S. Kulmala, A.C. Ferrari, Nano Lett. 11, 3190 (2011).  
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P.M. Campbell, X. Weng, J. Stitt, M.A. Fanton, E. Frantz, 
D. Snyder, B.L. Van Mil, G.G. Jernigan, R.L. Myers-Ward, 
C.R. Eddy Jr., D.K. Gaskill, Nano Lett. 9, 2873 (2009).  
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V.V. Bashevoi, S.L. Bogomolov, O.N. Borisov, 
V.A. Buzmakov, I.A. Ivanenko, O.M. Ivanov, 
N.Yu. Kazarinov, I.V. Kolesov, V.I. Mironov, A.I. Papash, 
S.V. Pashchenko, V.A. Skuratov, A.V. Tikhomirov, 
M.V. Khabarov, A.P. Cherevatenko, N.Yu. Yazvitskii, 
Phys. Partic. Nucl. Lett. 5, 33 (2008).  
8. Y. Hao, Y. Wang, L. Wang, Z. Ni, Z. Wang, R. Wang, 
C.K. Koo, Z. Shen, J.T.L. Thong, Small 6, 195 (2010).  
9. A. Eckmann, A. Felten, A. Mishchenko, L. Britnell, 
R. Krupke, K.S. Novoselov, C. Casiraghi, Nano. Lett. 12, 
3925 (2012). 
 


Raman Study of CVD Graphene Irradiated by Swift Heavy Ions

Electronic Sumy State University Institutional Repository

JOURNAL OF NANO- AND ELECTRONIC PHYSICS ЖУРНАЛ НАНО- ТА ЕЛЕКТРОННОЇ ФІЗИКИ Vol. 9 No 3, 03020(4pp) (2017) Том 9 № 3, 03020(4cc) (2017)   2077-6772/2017/9(3)03020(4) 03020-1  2017 Sumy State University Raman Study of CVD Graphene Irradiated by Swift Heavy Ions  E.A. Kolesov1, M.S. Tivanov1,*, O.V. Korolik1, P. Yu. Apel2,3, V.A. Skuratov2,3,4, A.M. Saad5, I.V. Komissarov6, A. Swic7, P.V. Żukowski8, T.N. Koltunowicz8,†  1 Belarusian State University, 4, Nezavisimosti Ave., 220030 Minsk, Belarus 2 Joint Institute for Nuclear Research, 6, Joliot-Curie, 141980 Dubna, Russia 3 Dubna State University, 141980 Dubna, Russia 4 National Research Nuclear University MEPhI, Moscow, Russia 5 Al-Balqa Applied University, PO Box 4545, 11953 Amman,  Jordan  6 Belarusian State University of Informatics and Radioelectronics, 6, P. Brovka Str., 220013 Minsk, Belarus 7 Institute of Technological Systems of Information, Lublin University of Technology, 20-618 Lublin, Poland 8 Department of Electrical Devices and High Voltage Technology, Lublin University of Technology, 20-618 Lublin, Poland  (Received 28 Febriary 2017; revised manuscript received 19 March 2017; published online 30 June 2017)  CVD-graphene on silicon was irradiated by accelerated heavy ions (Xe, 160 MeV, fluence of 1011 cm-2) and characterized by Raman spectroscopy. The defectiveness of pristine graphene was found to be domi-nated by grain boundaries while after irradiation it was determined by both grain boundaries and vacan-cies. Respectively, average inter-defect distance decreased from  ~ 24 to ~ 13 nm. Calculations showed that the ion irradiation resulted in a decrease in charge carrier mobility from ~ 4.0 × 103 to ~ 1.3·103 cm2/V s. The results of the present study can be used to control graphene structure, especially vacancies concen-tration, and charge carrier mobility.  Keywords: Irradiated graphene, Defects, Raman spectroscopy, CVD, Swift heavy ions.  DOI: 10.21272/jnep.9(3).03020 PACS numbers: 81.05.ue, 61.48.Gh, 78.30.Ly, 61.80. – x                                                           * tivanov@bsu.by † t.koltunowicz@pollub.pl 1. INTRODUCTION  Graphene is a promising material for a variety of applications. It is a two-dimensional sp2-carbon allotrope [1]. The importance of graphene studies is driven by its unique physical properties: optical transparency, high values of rigidity, thermal and electrical conductivity [2]. At present, graphene is used in transparent electrodes, field effect transistors, biosensors, etc. For several applications, graphene structure modification using controlled defect introduction is needed [3]. Swift heavy ions (SHI) irradiation method is a versatile and convenient tool for this purpose [4]. It allows one to create defects using a wide ion energy range, different fluences for obtaining different defect densities, and various ion types. However, the mechanism of defect formation in SHI-irradiated graphene is still unclear. Raman spectroscopy is a versatile tool for obtaining information on structural properties of various materials. This method is particularly useful in the context of graphene studies, due to monoatomic thickness of the material [1, 2]. As shown in [5], it is possible to determine the average inter-defect distance in laser spot area for graphene from D and G peaks maximum intensity ratio. Moreover, the correlation presented in [6] allows one to estimate graphene charge carrier mobility from the full width at half-maximum (FWHM) of 2D peak. Purpose of the present work is to study structural properties of SHI-irradiated graphene using Raman spectroscopy in order to understand how defect-caused structural changes influence graphene physical properties.  2. EXPERIMENTAL  Graphene studied in this paper was obtained by atmospheric pressure chemical vapor deposition (CVD). Prior to the synthesis, copper substrate was electrochemically polished in 1 M phosphoric acid solution for 5 min with operating voltage of 2.3 V. Synthesis was performed in a tubular quartz reactor with a diameter of 14 mm. Copper foil was pre-annealed at 1050°C for 60 min under the following gas flow rates: hydrogen 150 cc/min, nitrogen 100 cc/min. Synthesis was performed under the following conditions: reactor temperature 1050 °C, C10H22 flow rate 4 μl/min, H2 flow rate 60 cc/min, N2 carrier flow rate 100 cc/min, synthesis time 30 min. After the hydrocarbon flow termination, the sample was cooled down to room temperature at a rate of ~ 50 C/min. Graphene was transferred to Si/SiO2 substrate by wet-chemical room-temperature etching without polymer support in two steps. First, one side of copper foil was treated for 3 min in a solution of H2NO3 and H2O mixed in a volume ratio of 1:3. Then the copper foil was totally dissolved in a water solution of FeCl3. Graphene film was washed several times in a bath with distilled water prior to being placed onto the substrate. Graphene was irradiated by 160 MeV xenon ions with total fluence of 1011 cm – 2 at the IC100 cyclotron at the FLNR JINR in Dubna [7]. Ion beam homogeneity  E.A. KOLESOV, M.S. TIVANOV, O.V. KOROLIK ET AL. J. NANO- ELECTRON. PHYS. 9, 03020 (2017)   03020-2 over the irradiated specimen surface was controlled using beam scanning in the horizontal and vertical directions and was better than 5 %. Raman spectra were obtained with a spectral resolution not less than 3 cm – 1 using a confocal Raman spectrometer Nanofinder HE (LOTIS TII). For excitation of Raman radiation, a continuous wave solid-state laser with a wavelength of 473 nm was used. Room-temperature Raman measurements were carried out using laser power of 800 µW, the diameter of laser spot on the sample surface being about 0.6 µm.  3. RESULTS AND DISCUSSION  Typical Raman spectra for graphene before and after SHI irradiation are presented in Fig. 1. The presence of single-layer graphene in both cases is indicated by I2D/IG peak intensity ratios together with 2D peak FWHMs and single Lorentzian approximations (insets in Fig. 1) [2, 8].  1200 1500 1800 2100 2400 2700D'2500 2600 2700 2800 2900Intensity, arb. un.Raman Shift, cm-1FWHM = 44 cm-12500 2600 2700 2800 2900Intensity, arb. un.Raman Shift, cm-1FWHM = 38 cm-1Intensity, arb. un.Raman Shift, cm-1DG2D  Fig. 1 – Typical Raman spectra for graphene before (top) and after (bottom) ion irradiation. Insets:  2D peak approximations with single Lorentz functions  As seen from the figure, D peak in pristine graphene spectrum has relatively low intensity (ID/IG ~ 0.3), which corresponds to a low defectiveness of the sample structure [1, 2]. A different situation is observed for irradiated graphene: typical Raman spectra in this case demonstrate ID/IG intensity ratios not less than ~ 0.5. However, in several areas ID/IG values up to of ~ 1.0 are observed. Based on this fact, we can conclude that graphene defectiveness increased after irradiation. According to [5], the average inter-defect distance in the laser spot area LD can be calculated from the ratio of D and G peak maximum intensities using the following expression:   132 24 44.3 10 ( )( )( )( )DLI DL nmI GE eV     , (3.1)  where EL is an excitation energy. It is important to note that since the ID/IG ratio does not depend on a defect geometry [9], LD values calculated from the formula represent the average inter-defect distance for all Raman active defects that are involved in elastic scattering (since the process leading to D peak arising includes inelastic electron-phonon scattering and elastic electron-defect scattering events [2]). The calculation results were averaged over all obtained spectra (400 spectra for each sample). For pristine graphene, the obtained inter-defect distance value was ~ 24 nm. The calculation has shown that after the irradiation the LD value decreased to ~ 13 nm, signifying the increased number of defects. At the same time, calculated average distance between the ions fallen onto graphene surface is ~ 16 nm. In order to obtain detailed information on defect distribution over graphene surface before and after the irradiation, Raman mappings across the surface were performed. Fig. 2 presents LD maps for graphene both before and after the irradiation. As seen from Fig. 2, the distribution of LD is regular over all scanned area both for pristine and irradiated graphene. The inter-defect distance uniformly decreased (and therefore the defect density increased) after the irradiation. In [9] it was shown that graphene defect type can be obtained from ID/ID’ intensity ratio. D’ peak for graphene is usually partially overlapped with G peak leading to combined asymmetric shape, as can be observed in Fig. 1, but its intensity can be easily obtained by simple deconvolution. Typical spectra of pristine graphene demonstrate ID/ID’ values of 1.0 - 3.5 corresponding to grain boundaries. At the same time, irradiated graphene spectroscopy data shows ID/ID’ ~ 3.9 - 5.7. According to presented in [9] dependencies, these values indicate presence of both grain boundaries and vacancies. Fig. 3 shows Raman maps of the ID/ID’ intensity ratio giving the distribution of defect types over the scanned area.  RAMAN STUDY OF CVD GRAPHENE IRRADIATED BY SWIFT HEAVY IONS J. NANO- ELECTRON. PHYS. 9, 03020 (2017)   03020-3     Fig. 2 – Raman maps (20 × 20 m) of the average inter-defect distance for pristine (top) and irradiated (bottom) graphene; scanning step of 1 m  It is seen from the figure that scanned pristine graphene area is dominated by grain boundaries. In turn, irradiated graphene map contains a large number of vacancies besides the boundaries. Moreover, Raman maps of LD and ID/ID’ for irradiated graphene show a very strong correlation, giving almost identical values distribution. This fact indicates that nearly all defects in this case are represented by vacancies induced during the irradiation. According to [6], charge carrier mobility μ in graphene can be determined from 2D peak full width at half-maximum (FWHM). The authors of [6] used combined Hall effect measurements and Raman spectroscopy. This method resulted in finding strong correlation between Hall mobility and 2D peak FWHM. Determination performed according to dependencies described in [6] gave the value of charge carrier mobility in pristine graphene averaged over all 400 scanned spectra pr ~ 4.0·103 cm2/V s. For irradiated graphene, the average μirr was about 1.3·103 cm2/V s. The charge carrier mobility decrease after the irradiation can be explained by intensifying of charge carriers scattering by defects induced.  4. CONCLUSION  Raman studies of CVD-graphene on silicon substrate     Fig. 3 – Raman maps (20 × 20 m) of the ID/ID’ intensity ratio for pristine (top) and irradiated (bottom) graphene; scanning step of 1 m. Types of defects corresponding to specific ID/ID’  values are indicated under the scale  substrate irradiated by accelerated heavy ions (Xe, 160 Me V, fluence 1011 cm – 2) have shown the uniform distribution of defect types and inter-defect distances over graphene surface. The defectiveness of pristine graphene was dominated by grain boundaries while after irradiation it became determined by both grain boundaries and vacancies. The average inter-defect distance was found to decrease from ~ 24 to ~ 13 nm. Charge carrier mobilities in graphene before and after the ion irradiation were calculated. It was found that the irradiation resulted in a decrease of charge carrier mobility from ~ 4.0·103 to ~ 1.3·103 cm2/V s. The results of the present study can be used to control graphene structure, especially vacancies concentration, and charge carrier mobility.  AKNOWLEDGEMENTS  This work was partly supported by the statute tasks of the Lublin University of Technology, at the Faculty of Electrical Engineering and Computer Science,  (S-28/E/2017), entitled “Researches of electrical, magnetic, thermal and mechanical properties of modern electrotechnical and electronic materials,   E.A. KOLESOV, M.S. TIVANOV, O.V. KOROLIK ET AL. J. NANO- ELECTRON. PHYS. 9, 03020 (2017)   03020-4 including nanomaterials and electrical devices and their components, in order to determination of suitability for use in electrical engineering and to increase the efficiency of energy management”.   REFERENCES  1. A.C. Ferrari, J.C. Meyer, V. Scardaci, C. Casiraghi, M. Lazzeri, F. Mauri, S. Piscanec, D. Jiang, K.S. Novoselov, S. Roth, A.K. Geim, Phys. Rev. Lett. 97, 187401 (2006).  2. A.C. Ferrari, D.M. Basko, Nature Nanotech. 8, 235 (2013).  3. A.K. Geim, Science 324, 1530 (2009).  4. J. Zeng, H.J. Yao, S.X. Zhang, P.F. Zhai, J.L. Duan, Y.M. Sun, G.P. Li, J. Liu, Nucl. 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CVD-graphene on silicon was irradiated by accelerated heavy ions (Xe, 160 MeV, fluence of 1011 cm 2) and characterized by Raman spectroscopy. The defectiveness of pristine graphene was found to be dominated by grain boundaries while after irradiation it was 
determined by both grain boundaries and vacancies. Respectively, average inter-defect distance decreased from~ 24 to~ 13 nm. Calculations showed that the ion irradiation resulted in a decrease in charge carrier mobility from~ 4.0× 103 to~ 1.3• 103 cm2/V s. The results of the present study can be used to control graphene structure, especially vacancies concentration, and charge carrier mobility

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Raman study of CVD graphene irradiated by swift heavy ions

CVD-graphene on silicon was irradiated by accelerated heavy ions (Xe, 160 MeV, fluence of 1011 cm 2) and characterized by Raman spectroscopy. The defectiveness of pristine graphene was found to be dominated by grain boundaries while after irradiation it was determined by both grain boundaries and vacancies. Respectively, average inter-defect distance decreased from ~ 24 to ~ 13 nm. Calculations showed that the ion irradiation resulted in a decrease in charge carrier mobility from ~ 4.0 × 103 to ~ 1.3•103 cm2/V s. The results of the present study can be used to control graphene structure, especially vacancies concentration, and charge carrier mobility

Zukowski, P. V.

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https://essuir.sumdu.edu.ua/bitstream/123456789/65870/1/jnep_V9_03020_4.pdf

Raman Study of CVD Graphene Irradiated by Swift Heavy Ions

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