Materials Transactions, Vol. 47, No. 7 (2006) pp. 1847 to 1852
#2006 The Japan Institute of Metals
EXPRESS REGULAR ARTICLE
Correlation between ID =IG Ratio from Visible Raman Spectra and sp2 /sp3 Ratio
from XPS Spectra of Annealed Hydrogenated DLC Film
F. C. Tai1; * , S. C. Lee1 , C. H. Wei2 and S. L. Tyan3
1
Department of Material Science and Engineering, National Cheng-Kung University, Tainan 701, Taiwan
Department of Mechanical Engineering, TATUNG University, Taipei 104, Taiwan
3
Department of Physics, National Cheng-Kung University, Tainan 701, Taiwan
2
The hydrogened diamond like carbon film (DLCH) with 1 mm thickness is made by hydrocarbon gas ion beam deposition method. The
relationship between ID =IG ratio fitted from visible Raman spectra and sp2 /sp3 ratio done from XPS spectra of DLCH film shows a trend. The
ID =IG ratio of deconvoluted visible Raman spectra shows a correlation with sp2 /sp3 ratio from XPS spectra as annealing temperature increases,
the graphitization and the disorder increase. The ID =IG ratios fitted with two-curve Gaussian functions of Raman spectra tend to be proportional
to sp2 /sp3 ratio fitted with three-curve with 100% Gaussian function of XPS spectra when post annealed treatment is below 400 C and without
severe oxidation. [doi:10.2320/matertrans.47.1847]
(Received March 6, 2006; Accepted May 22, 2006; Published July 15, 2006)
Keywords: hydrogenated diamond like carbon (DLCH) film, Raman spectra, XPS spectra, ID =IG ratio, sp2 /sp3 ratio
1.
Introduction
It is well known that there are a lot of analytical techniques
used to quantify the versatile properties of diamond-like
carbon (DLC) film from different manufacturing processes.1)
Among these tools, spectrum shape fitting is a useful method
to show the detail structure of carbon films. There are two
kinds of quantitative indexes that can evaluate DLC’s
characteristics; one is ID =IG ratio which is often used to
evaluate the disorder of carbon networks, ID means the
intensity of decomposed D (disorder) peak due to the A1g D
breathing carbon bonded modes of sp2 disordered carbon
atoms sites as aromatic rings structure, and IG means the
intensity of decomposed G (graphite) peak resulted from the
E2g G stretching carbon bonded mode of all pairs of sp2
disordered atoms as both aromatic and olefinic molecules.
Visible Raman spectroscopy with 488 or 514 nm wavelength
is the most popular tool to measure ID =IG ratio due to the
nondestructive nature and easy operation.2,3) The other index
is sp2 /sp3 ratio which is used to evaluate the graphitization of
carbon networks. In this index sp2 means the intensity of
decomposed sp2 peak with graphite-like property due to
trigonal coordination carbon network and sp3 means the
intensity of decomposed sp3 peak with diamond-like property
due to tetrahedral coordination carbon network. X-ray
photoelectron spectroscopy (XPS) is the better method to
measure sp2 /sp3 ratio compared with Auger electron spectroscopy (AES), electron energy loss spectroscopy (EELS),
nuclear magnetic resonance (NMR) due to measuring
superiorities.4–6) In finding the correlation between ID =IG
ratio and sp2 /sp3 ratio of non-hydrogenated Diamond-Like
Carbon film (DLC) film, some studies have used Raman
spectra associated with EELS or XPS.7–12) But for DLCH
film, due to the spectrum of visible Raman contains a much
larger scattering cross section of sp2 than that of sp3 up to 50–
230 times,13) it is very difficult to detect the sp3 content when
the sp3 content in DLCH film is small. As a result, visible
Raman can’t be directly applied to probe sp2 /sp3 ratio. The
*Corresponding
author. E-mail: [email protected]
sp2 /sp3 ratio then can be quantified by Tamor’s data fitting
curve of optical Tauc gap energy by calculating the sp3
component measured by EELS or NMR as noted by Ferrari.2)
The purpose of this study is to find out a correlation between
ID =IG ratio by visible Raman and sp2 /sp3 ratio by XPS of
DLCH films under post annealed treatment.
2.
Experimental Procedure
DLCH film was performed by direct carbon ion beam
deposition (IBD) method with hydrocarbon gas to deposit on
600 (100)-oriented p-type single-side polished silicon wafer.
The vacuum chamber was installed with four sets of ion beam
sources, when the base pressure reaches the 5 104 Pa with
Ar as purging gas, then the reactive hydrocarbon gas was fed
through the ion source with special Reflector Anode Hot
Wire Filament to accelerate these ionized species until stable
working pressure reached at 0.1 Pa. The DLCH growth
temperature was controlled at 200 C, and the final deposited
thickness was 1.0 mm. The typical hydrogen content of
DLCH films deposited by IBD method ranged from 30 to
40 at%.1) The post annealed temperatures of thermal treatment were set at 300 C, 350 C and 400 C under N2
atmosphere for one hour, respectively.
Raman spectroscope was used to confirm the amorphous
structural characteristic of DLCH film, the Arþ laser wavelength was 488 nm and the probe aperture was near 10 mm, in
order to avoid local heating accumulation during film
detection, the lower laser power output (14 mW) was used
and substrate holder was controlled at 77 K from liquid N2 ,
there is no visible damage before and after Raman test. The
curve-fitting of raw Raman line was deconvoluted into twocurve with one linear background normalization. According
to automatic fitting of integrated area it is not necessary to fix
the D and G peak position and full width at half maximum
(FWHM), respectively. XPS tool (Model Escalab 210) used
Al k-alpha radiation (1486.6 eV) and chose polyethylene as
calibration sample (C1s spectrum was set at 284.6 and its sp2
is zero percent). There is no Arþ sputtering as pre-clean
treatment in order to avoid hybridization transformation of
1848
F. C. Tai, S. C. Lee, C. H. Wei and S. L. Tyan
Table 1
Material
Multi-peaks Fitting function
2
XPS C1s spectra deconvolution of carbon films.
Sp band
Sp3 band
Sp2 satellite band CO band
Sp2 /Sp3 ratio C1s vs. O1s intensity Ref.
a-C
2
X%Gaussian
+ Y%Lorentzian
284.30
285.20
N/A
N/A
60/40
N/A
15)
a-C
3
X%Gaussian
+ Y%Lorentzian
284.40
285.20
N/A
286.50
67/33
3.0% O[AT]
16)
a-C
3
80%Gaussian
284.84
+ 20%Lorentzian
285.80
286.85
287.00
67/33
8.0–10.0% O[AT]
17)
a-C
4
100% Gaussian
285.80
286.90
287.00
80/20
C1s<O1s
18)
a-C:H
2
80%Gaussian
Esp2
+ 20%Lorentzian
Esp2 +0.50
N/A
Esp2 +0.50 47/53
C1s>O1s
19)
a-C:H
3
N/A
285.05
N/A
286.40
10.0% O[AT]
20)
3
80%Gaussian
Esp3 0.5 variable
+ 20%Lorentzian
Esp 0.50 40/60
C1s>O1s
21)
a-C:H
284.80
284.30
N/A
20/80
3
4
N/A
284.50
285.30
286.60
287.70
88/12
N/A
22)
a-C:H:Cr
1
284.60
N/A
N/A
288.60
N/A
Air oxidation
23)
a-C:H:Ar
3
N/A
X%Gaussian
+ Y%Lorentzian
284.50
285.30
N/A
286.50
26/74
N/A
24)
a-C:H:Si
3
N/A
284.00
284.70
N/A
287.00
N/A
9.2–12.9% O[AT]
25)
a-C:H:N
4
100% Gaussian
284.5
285.50 (C=N) 286.20 (C-N)
287.40
N/A
N/A
26)
a-C:H:N
4
100% Gaussian
282.20
284.80
C-N (289.0)
286.50
63/37
N/A
27)
a-C:H:F
4
N/A
< 284:9
N/A
N/A
287.4
N/A
N/A
28)
carbon atom and different sputtering yield during ion
bombardment procedure on top 5 nm depth of near surface
of DLCH film.4,14) XPS was performed to estimate the sp2 /
sp3 area ratio resulting from relative sp2 and sp3 contents of
the DLCH film. The curve-fitting of raw XPS C1s line was
also deconvoluted into two-curve, three-curve and four-curve
types with linear background normalization. All the key
parameters were allowed to vary under adopting automatic
fitting of integrated area method in order to get the
appropriate fitting results, e.g. sp2 , sp3 , sp2 satellite, CO
(C–O or C=O) peak positions and FWHM, respectively. The
raw XPS lines were automatically calculated by 100%
Gaussian function and multi-peaks assignment to get analytical peak. Table 1 summarizes the XPS C1s spectra
deconvolution of carbon films, including amorphous carbon
film (a-C), a-C:H (DLCH) and a-C:H:X (doping cases), the
different curve fitting methods using 80% up to 100%
Gaussian functions consist of two, three or four deconvoluted
peaks in order to quantitatively evaluate the sp2 /sp3
ratio.15–28) Diez et al. have mentioned that the Gaussian
function could be used to account for the instrumental energy
resolution and chemical disorder, and the Lorentzian function
could be used to measure the life time of photoionzation
process.15)
3.
Results and Discussion
3.1 Evaluation of ID =IG ratio by Raman analysis
Figure 1 shows the typical and deconvoluted Raman
spectra of disordered graphite of as-deposited and annealed
DLCH film. In general, two-curve Gaussian function is
simple and sufficient to decompose the single Raman spectra
into two peaks. The deconvoluted D peak means the disorder
carbon bonding centered at around 1350 cm1 and G peak
means the graphite carbon bonding located at around
1580 cm1 .2,29) As increasing the annealed temperature, the
Intensity (a.u.)
a-C:H
400°C
350°C
300°C
G
D
as-deposited
1000
1200
1400
1600
1800
2000
-1
Raman Shift, r / cm
Fig. 1 Raman spectra of as-deposited and annealed DLCH films, the D and
G peaks are deconvoluted by two-Gaussian peaks.
D peak gradually grows and its height is less than that of
G peak until severe annealed treatment under higher temperature, which means the DLCH film becomes less diamondlike due to annealed treatment. These Raman lineshapes have
a slight skewed potential for D and G peak to shift higher
peak position when DLCH films are annealed from asdeposited to 400 C state. The variation of both G peak
position, G peak position and ID =IG area ratio are common
criteria for evaluation about post-annealed treatment of
DLCH film. Figure 2 reveals the G peak position and FWHM
of G peak under peak’s integral intensity measured by 100%
Gaussian and two-curve fitting method under as-deposited
and annealed conditions. The result shows the G peak
position shifts from 1555 cm1 (as-deposited) to 1566 cm1
(annealed at 400 C) but FWHM of G peak gradually
decreases from 142 cm1 to 123 cm1 , respectively. This
trend is agreement with the studies of Chiu and Tallant et
Correlation between ID =IG Ratio from Visible Raman Spectra and sp2 /sp3 Ratio from XPS Spectra of Annealed Hydrogenated DLC Film
1849
as-deposited
140
C1s
130
120
110
100
0
50
100
150
0
50
100
150
200
250
300
350
400
450
200
250
300
350
400
450
G Peak Position, p / cm
-1
1600
Intensity (a.u.)
-1
G Peak FWHM, p / (cm )
150
O1s
Auger O (KLL)
1580
1560
1540
1520
1500
0
Annealed Temperature, T / °C
200
400
600
800
1000
Binding Energy, Ε /eV
Fig. 2 G peak position and FWHM of G peak as a function of annealed
temperature of DLCH films, 25 C sample means the as-deposited state.
4.0
Fig. 4 Typical survey scan spectrum of DLCH film.
Uglov et al, a-C film by CAVD method
this work
Chiu et al, Cr-DLCH by CAE method
Oral et al, a-C:H film by PECVD method
Tang et al, DLCH film by MSIBD method
3.5
C1s spectra
285.2
400°C
350°C
300°C
as-deposited
284.8
3.0
Intensity (a.u.)
ID/IG ratio
2.5
2.0
1.5
1.0
0.5
0.0
0
50
100
150
200
250
300
350
400
450
500
Annealed Temperature, T / °C
Fig. 3 ID =IG ratio as a function of annealed temperature. 25 C samples
mean the as-deposited states.
23,30–36)
al.
Figure 3 displays the ID =IG ratio as a function of
annealed temperature and compared to other papers.23,31,32,37)
It can be verified that the as-deposited DLCH film contains
the diamond-like property due to its ID =IG ratio (1.72) is
similar to reports from Ma (1.30), Sung (1.70), Sheeja (1.76)
and Zhang (1.80), which are especially characterized on
hardness performance.38–41) The ID =IG ratio increases from
1.72 to 2.04 with increasing annealed temperature from asdeposited to 400 C with one significant variance at 300 C
and this means that annealed DLCH starts to increase its
disorder performance at this critical temperature, these values
are consistent with the experimental result by Tallant, Oral
and Tang et al.30–36) According to these characteristics, the
annealed DLCH film has slight graphitization when heating
up to 300 C, this critical temperature is in agreement with the
study that thermal annealing treatment would lead to lose the
hydrogen and result in the graphitization conversion for C-C
sp3 bonded carbon to transform to C-C sp2 bonded carbon.33)
On the other hand, 350 C and 400 C post annealed treatment
result in a more significant change of DLCH films.
275
280
285
290
295
300
Binding Energy, Ε /eV
Fig. 5 XPS C1s spectra of DLCH films.
3.2 Evaluation of sp2 /sp3 ratio by XPS analysis
The XPS C1s and O1s scan spectra of as-deposited of
DLCH film is shown in Fig. 4. The major characteristic is the
relative height of C1s peak is higher than O1s peak.
According to the peak area and sensitive factor of carbon
(SF is 1.00) and oxygen atom (SF is 2.93), it is easy to obtain
the chemical composition of DLCH films from the measurement of normalized area. The ratio of oxygen to carbon
atomic fraction values for as-deposited, 300 C, 350 C and
400 C are 10.9/89.1(0.12), 12.3/87.7(0.14), 14.6/85.6(0.17)
and 15.1/84.9(0.18), respectively. These data indicate the
oxygen content will increase with increasing annealed
temperature even though the thermal treatment is filled with
N2 circulation. This content of oxygen is only slightly higher
than previous works20,25) and is assumed to cause no effect on
measuring the contents of sp2 and sp3 contents in DLCH film.
Figure 5 shows the XPS C1s spectra of as-deposited and
annealed DLCH film. These peaks of lineshapes seem to shift
lower binding energy site from 285.2 eV of as-deposited
sample to 284.8 eV of annealed one at 400 C with a
difference of 0.4 eV and the XPS C1s spectra broadens from
1850
F. C. Tai, S. C. Lee, C. H. Wei and S. L. Tyan
O1s spectra
(a)
533
532.2
as-deposited
400°C
350°C
300°C
as-deposited
2
Intensity (a.u.)
Intensity (a.u.)
sp
Fitting not well
3
sp
280
520
525
530
535
540
285
545
290
295
Binding Energy (eV)
Binding Energy, E / eV
Fig. 6
XPS O1s spectra of DLCH films.
as-deposited
2
sp
CO
3
sp
280
285
290
295
Binding Energy (eV)
(c)
as-deposited
2
sp
Intensity (a.u.)
FWHM at 1.65 eV of as-deposited sample to 1.78 eV of
annealed one at 400 C with a difference of 0.13 eV. XPS O1s
spectra also shifts from binding energy at 533.0 eV of asdeposited sample to 532.2 eV of annealed one at 400 C with
a difference of 0.8 eV and the XPS O1s spectra broadens
from FWHM at 2.13 eV of as-deposited sample to 2.89 eV of
annealed one at 400 C with a difference of 0.76 eV, as shown
in Fig. 6, these trends of XPS C1s and O1s spectra are similar
to the findings of the severe oxidation under post annealed at
300 C (noted that at 400 C the Cr-DLCH film is severely
damaged and completely disappeared) for 30 minutes under
air ambient (Chiu et al.23)). Figures 7(a), (b) and (c) show the
deconvolution results of XPS C1s line by using two curvefitting, three curve-fitting and four curve-fitting methods with
100% Gaussian function, respectively. The binding energy
assigned to sp2 , sp3 , sp2 satellite and CO part ranges from low
energy site to high energy site. The asymmetric component is
located at the higher binding energy site. By comparing to
Raman spectra, the obvious characteristics of XP1 C1s
spectrum is that the curve is asymmetric and the nondeconvoluted peak position ranges around 285.0 eV with a
deviation of 0.2 eV where the peaks comes from the C-C, CH and C-OH bonds of DLCH film. It is easy to break these
bonds with appropriate thermal energy but it is hard to
separate these relative components.14) Franta et al.42) have
proposed optical dispersion model to illustrate the linear
relation between annealed temperature and sp2 /sp3 ratio of
DLCH deposited by PECVD method. Diaz et al.15) also have
found the same trend from a-C film by laser evaporation.
From these trends and the fitting accuracy of Fig. 7(a), it is
concluded that the two-curve fitting method is not a suitable
choice in order to separate the sp2 and sp3 contents, as shown
in Fig. 8. It is noted that the sp2 /sp3 ratio increase from 3.70
to 6.25 with increasing annealed temperature from asdeposited to 400 C, which means that DLCH film starts
gradual graphitization and the graphite-like part increases
with increasing temperature under annealed treatment.
Figure 9 shows the XPS O1s spectra of as-deposited and
annealed DLCH film, and there exists a trend that the CO
content increases with oxygen content either by three-curve
fitting or four-curve fitting method on C1s spectrum. But by
comparison with sp2 /sp3 ratio chart and oxygen content of
Intensity (a.u.)
(b)
2
sp satellite
CO
3
sp
280
285
290
295
Binding Energy (eV)
Fig. 7 (a) Two-Gaussian peaks fitting deconvolution of XPS C1s spectra of
DLCH films, (b) and (c) are three and four peaks.
XPS measurement results, the three-curve fitting demonstrates a better relationship between oxygen content and CO
content than the four-curve fitting. Finally, it is reasonable to
determine the relationship between ID =IG ratio and sp2 /sp3
ratio (Fig. 10) by combining the Figs. 3 and 8. For DLCH
film when post annealed treatment is under 400 C with slight
oxidation, the ID =IG ratio could correlate linearly with sp2 /
sp3 ratio by adopting the three-cure fitting method with 100%
Gaussian function, and this trend is similar to the findings of
Ferrari, Reisel and Zhang et al. by using Raman and
EELS.2,6,43)
Correlation between ID =IG Ratio from Visible Raman Spectra and sp2 /sp3 Ratio from XPS Spectra of Annealed Hydrogenated DLC Film
10
1851
4.0
four-curve fitting
three-curve fitting
two-curve fitting
9
Ferrari et al, a-C:H film by NMR and EELS analysis
3.5
8
3.0
2.5
ID/IG Ratio
6
3
sp /sp ratio
7
2
5
4
this work (XPS)
2.0
1.5
Zhang et al, a-C and a-C:H film by EELS analysis
3
1.0
Reisel et al, a-C:H:N by NMR analysis
2
0.5
1
0
0.0
0
100
200
300
400
500
0
1
2
3
4
5
2
Annealed Temperature, Τ / °C
6
7
8
9
10
3
sp /sp ratio
Fig. 8 sp2 /sp3 ratio as a function of annealed temperature by multiGaussian peaks fitting deconvolution of XPS C1s of DLCH film.
Fig. 10 ID =IG ratio as a function of sp2 /sp3 ratio by three-Gaussian peaks
fitting method of XPS C1s of DLCH film.
Acknowledges
40
The authors thank the assistance from the Cosmovac
Company for deposition the DLCH film and Dr. C.H. Wu of
Prof. S. L. Tyan Laboratory (Department of Physics, NCKU)
for Raman measurement and discussion.
four-curve fitting
three-curve fitting
35
CO percent (%)
30
REFERENCES
25
20
15
10
8
10
12
14
16
18
Oxygen content (at%)
Fig. 9 CO percentage as a function of oxygen content by multi-Gaussian
peaks fitting deconvolution of XPS C1s of DLCH film.
4.
Conclusions
The hydrogened diamond like carbon film (DLCH) with
1 mm thickness is deposited by direct hydrocarbon gas ion
beam method on silicon wafer. Experimental results show
that according to automatic fitting of integrated area it is not
necessary to fix the peak position, peak height and FWHM of
Raman and XPS spectral lineshapes for curve deconvolution
of DLCH film when post annealed treatment is below 400 C
and under little oxidation. Both the ID =IG ratio deconvoluted
from visible Raman spectra begins to increase the disorder
and the sp2 /sp3 ratio separated from XPS spectra starts to
show graphitization in the DLCH film at 300 C during post
annealing treatment. The other important experimental result
is that the ID =IG ratio calculated from two-Gaussian peaks
method of Raman spectra could correlate linearly with sp2 /
sp3 ratio adopted from three-Gaussian peaks method of XPS
spectra under 400 C post annealed treatment.
1) B. Bhushan: Diamond Relat. Mater. 8 (1999) 1985–2015.
2) A. C. Ferrari and J. Robertson: PRB 61 (2000) 14095–14107.
3) G. Adamopoulos, K. W. R. Gilkes, J. Robertson, N. M. J. Conway,
B. Y. Kleinsorge, A. Buckley and D. N. Batchelder: Diamond Relat.
Mater. 8 (1999) 541–544.
4) L. Calliari: Diamond Relat. Mater. 14 (2005) 1232–1240.
5) A. LiBassi, A. C. Ferrari, V. Stolojan, B. K. Tanner, J. Robertson and
L. M. Brown: Diamond Relat. Mater. 9 (2000) 771–776.
6) A. Dorner-Reisel, L. Kubler, G. Irmer, G. Reisel, S. Schops, V. Klemm
and E. Muller: Diamond Relat. Mater. 14 (2005) 1073–1077.
7) F. Qian, R. K. Singh, S. K. Dutta and P. P. Pronko: Appl. Phys. Lett. 67
(1995) 3120–3122.
8) S. Prawer, K. W. Nugent, Y. Lifshitz, G. D. Lempert, E. Grossman,
J. Kulik, I. Avigal and R. Kalish: Diamond Relat. Mater. 5 (1996) 433–
438.
9) A. V. Stanishevsky and L. Yu. Khriachtchev: Diamond Relat. Mater. 5
(1996) 1355–1358.
10) A. V. Stanishevsky, L. Yu. Khriachtchev, R. lappalainen and M.
Rasanen: Diamond Relat. Mater. 6 (1997) 1026–1030.
11) L. Yu. Khriachtchev, R. lappalainen, M. Hakovirta and M. Rasanen:
Diamond Relat. Mater. 6 (1997) 694–699.
12) Z. Y. Chen, J. P. Zhao, T. Yano, T. Ooie, M. Yoneda and J. Sakakibara:
J. Appl. Phys. 88 (2000) 2305–2308.
13) D. L. Baptista and F. C. Zawislak: Diamond Relat. Mater. 13 (2004)
1791–1801.
14) F. L. Freire Jr., M. E. H. Maia da Costa, L. G. Jacobsohn and D. F.
Franceschini: Diamond Relat. Mater. 10 (2001) 125–131.
15) J. Diaz, G. Paolicelli, S. Ferrer and F. Comin: Phys. Rev. B 54 (1996)
8064–8069.
16) P. Merel, M. Tabbal, M. Chaker, S. Moisa and J. Margot: Appl. Surf.
Sci 136 (1998) 105–110.
17) S. T. Jackson and R. G. Nuzzo: Appl. Surf. Sci 90 (1995) 195–203.
18) J. Rao, K. J. Lawson and J. R. Nicholls: Surf. Coat. Technol. 197 (2005)
154–160.
19) T. Y. Leung, W. F. Man, P. K. Lim, W. C. Chan, F. Gaspari and
S. Zukotynski: J. Non-Cryst. Solids 254 (1999) 156–160.
20) M. Silinskas and A. Grigonis: Diamond Relat. Mater. 11 (2002) 1026–
1852
F. C. Tai, S. C. Lee, C. H. Wei and S. L. Tyan
1030.
21) J. Filik, P. W. May, S. R. J. Pearce, R. K. Wild and K. R. Hallam:
Diamond Relat. Mater. 12 (2003) 974–978.
22) M. Yoshida, T. Tanaka, S. Watanabe, M. Shinohara, J. W. Lee and
T. Takagi: Surf. Coat. Technol. 174 (2003) 1033–1037.
23) M. C. Chiu, W. P. Hsieh, W. Y. Ho, D. Y. Wang and F. S. Shieu: Thin
Solid Films 476 (2005) 258–263.
24) W. Zhang, A. Tanaka, K. Wazumi and Y. Koga: Thin Solid Films 416
(2002) 145–152.
25) X. Li, T. K. S. Wong, Rusli and D. Yang: Diamond Relat. Mater. 12
(2003) 963–967.
26) N. K. Cuong, M. Tahara, N. Yamauchi and T. Sone: Surf. Coat.
Technol. 193 (2005) 283–287.
27) L. X. Liu and E. Liu: Surf. Coat. Technol. 198 (2005) 189–193.
28) G. Q. Yu, B. K. Tay and Z. Sun: Surf. Coat. Technol. 191 (2005) 236–
241.
29) M. A. Tamor and W. C. Vassell: J. Appl. Phys. 76 (1994) 3823–3830.
30) D. R. Tallant, J. E. Parmeter, M. P. Siegal and R. L. Simpson: Diamond
Relat. Mater. 4 (1995) 191–199.
31) B. Oral, R. Hauert, U. Muller and K. H. Ernst: Diamond Relat. Mater. 4
(1995) 482–487.
32) Z. Tang, Z. J. Zhang. K. Narumi, Y. Xu, H. Naramoto, S. Nagai and
K. Miyashita: J. Appl. Phys. 89 (2001) 1959–1964.
33) R. Vuppuladhadium, H. E. Jackon and L. C. Wu: J. Appl. Phys. 77
(1995) 2714–2718.
34) J. Robertson: ADVANCES IN PHYSICS 35 (1986) 314–374.
35) A. C. Ferrari, B. Kleinsorge, N. A. Morrison, A. Hart, V. Stolojan and
J. Robertson: J. Appl. Phys. 85 (1999) 7191–7197.
36) N. K. Cuong, M. Tahara, N. Yamauchi and T. Sone: Surf. Coat.
Technol. 174–175 (2003) 1024–1028.
37) V. V. Uglov, A. K. Kuleshov, D. P. Rusalsky, M. P. Samzov and
A. N. Dementshenok: Surf. Coat. Technol. 158–159 (2002) 699–703.
38) F. Ma, Q. Chen, X. Cai, G. Li and H. Ma: Materials Transactions of The
Japan Institute of Metals 43 (2002) 1398–1402.
39) S. L. Sung, X. J. Guo, K. P. Huang, F. R. Chen and H. C. Shih: Thin
Solid Films 315 (1998) 345–350.
40) D. Sheeja, B. K. Tay, L. Yu and S. P. Lau: Surf. Coat. Technol. 154
(2002) 289–293.
41) Q. Zhang, S. F. Yoon, J. Ahn, Rusli, H. Yang, Bo Gan, C. Yang, F.
Watt, E. J. Teo and T. Osipowice: Diamond Relat. Mater. 9 (2000)
1758–1761.
42) D. Franta, V. Bursikova, I. Ohlidal, L. Zajickova and P. Stahel:
Diamond Relat. Mater. 14 (2005) 1795–1798.
43) S. Zhang, X. T. Zeng, H. Xie and P. Hing: Surf. Coat. Technol. 123
(2000) 256–260.