2. 576
PROTECTION OF METALS AND PHYSICAL CHEMISTRY OF SURFACES Vol. 51 No. 4 2015
ALI ARMAN et al.
RESULTS AND DISCUSSION
AFM images of samples 1–4 are shown in Fig. 1.
These images were used to estimate the mean size of
the nanoparticles. Figure 1e shows the abundant
topography of these samples as obtained from the
AFM data. This figure can be used to interpret the dis
tribution of particle sizes. The maximum abundance
gives the average particle size and the width provides
the variance of the particle diameter. As observed, the
average particle size of the Cu nanoparticles were 10,
10, 6, and 14 nm for samples 1, 2, 3 and 4, respectively.
The full width at the half maximum particle size distri
bution was not large for all samples.
The RMS roughness and the experimental PSD
profiles of thin films are shown in Fig. 2. Each PSD
plots was calculated using the FFT algorithm for 1 μm ×
1 μm AFM image data. It can be seen from Fig. 2h that
the PSD spectra of the thin film deposited at the Sam
ple 4 shows slower variation over the spatial frequency
[9–11]. This behavior is because of the particle size
and the amount of carbon in thin film [12]. It can be
seen that the RMS roughness values increased as the
thickness is increased Fig. 2f. It was observed that both
of the RMS roughness and PSD spectra change with
thickness and the amount of carbon in layers.
Figure 3 shows the x ray diffraction (XRD) pattern
of sample 2 on the glass and the x ray diffraction
(XRD) pattern of sample 2 with 10 min deposition
time for the Ni shell on the silicon. As shown, Cu
nanocrystals with (111), (200), and (220) orientations
Fig. 1. AFM images of samples (a) 1; (b) 2; (c) 3; (d) 4 and (e) the number of events for topography of samples 1–4.
3500
3000
2500
2000
1500
1000
500
0
5 25 30201510
(b)(а)
200 nm
(d)(c)
200 nm
200 nm200 nm
X: 1.0 µm
Y: 1.0 µm
Z: 25.5 nm
X: 1.0 µm
Y: 1.0 µm
Z: 34.3 nm
X: 1.0 µm
Y: 1.0 µm
Z: 20.1 nm
X: 1.0 µm
Y: 1.0 µm
Z: 2.1 nm
0
Abundance
Topography, nm
1
2
3
4
(e)
3. PROTECTION OF METALS AND PHYSICAL CHEMISTRY OF SURFACES Vol. 51 No. 4 2015
MICROSTRUCTURE AND OPTICAL PROPERTIES 577
and the Ni nanocrystals with (111) and (200) orienta
tions formed in the film. Traces of the Ni2O3 structure
in Fig. 2 indicate that the surface of the Cu@Ni core
shells oxidized upon exposure to air.
The UV VIS near IR absorption spectra of sam
ples 1–4, including Cu nanoparticles of different sizes,
are shown in Fig. 4. The electrical resistivity of the thin
film in samples 1 to 4 varies from several Ω to more
than 100 MΩ. In samples 3 and 2, an absorption peak
is observed at about 600 nm. This absorption peak is a
sign of the existence of Cu nanoparticles caused by
SPR [14]. An edge of strong absorption is observed for
all samples located above the SPR peak. This strong
absorption is dependent on the electrical resistivity of
the samples.
Figure 5 shows the UV VIS near IR absorption
spectra of sample 2 without the Ni layer and after 1, 7
and 10 min of Ni deposition. The SPR peak caused by
the Cu nanoparticle is damped by the increasing thick
ness of the Ni layer. The absorbance in near IR region
4.0
3.0
3.5
2.5
2.0
1.5
1.0
0.5
4.03.53.02.01.50.50 2.51.0
(f) (h)
RMS,nm
Number of Samples
–1.0
4
3
2
1
0
–1
–2
–3.0 –2.5 –2.0 –1.5
1
2
3
4
PSD[log(nm4)]
k[log({1/nm})}
Fig. 2. RMS roughness versus (f) and Power spectra density thin films (h).
40
20
80604020
0
Intensity,a.u.
2θ, deg
Intensity,a.u.
20 40 60 80
15
20
25
30
35
40
Cu(111)
Ni(111)
Cu(200)
Ni203
Si(311)
Cu(220)
Cu(111)
Cu(200)
(а) (b)
2θ, deg
Fig. 3. X ray diffraction profile pattern (a) sample 2 and (b) sample 2 of Cu@Ni nanoparticles sample 2 [13].
2500200015001000500
Absorbance,a.u.
Wavelength, nm
1
2
3
4
Fig. 4. UV VIS near IR spectra of samples 1 to 4, includ
ing Cu nanoparticles.
4. 578
PROTECTION OF METALS AND PHYSICAL CHEMISTRY OF SURFACES Vol. 51 No. 4 2015
ALI ARMAN et al.
increased as the thickness of the Ni layer increased. The
edge of absorption observed in the near IR region var
ied as the thickness of the Ni layer varied.
CONCLUSIONS
Cu@Ni core shell nanoparticles on a C:H thin
film were prepared by co deposition of RF sputtering
and RF PECVD. Samples with different Cu nanopar
ticle sizes were grown and then Ni layers of different
thicknesses were grown over the Cu nanoparticles.
AFM images and XRD profiles showed that a Cu
nanocrystal core and Ni nanocrystal shell formed on
the film. Also, It was observed that both of the RMS
roughness and PSD spectra change with thickness and
the amount of carbon in layers. An SPR peak for the
Cu nanoparticles was observed at about 600 nm and
was damped as the thickness of Ni layer increased.
Absorbance in the near IR region increased as the
thickness of the Ni layer increased. The edge of strong
absorption observed in the near IR region varied as
the thickness of the Ni layer varied.
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0.8
0.6
0.4
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2500200015001000500
0
Absorbance,a.u.
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Cu@Ni2
Cu@Ni1
Fig. 5. UV VIS near IR spectra for sample 2 without a Ni
layer and after 1, 7, and 10 min of Ni deposition.