Structure of polycrystalline diamond coatings deposited by СVD method in the plasma of glow discharge with the use of pulse power supply
The structure of CVD carbon coatings synthesized in a hydrogen-methane mixture in the plasma of a glow discharge stabilized by a magnetic field using a pulsed power supply was studied by X-ray diffraction analysis and optical microscopy. The range of deposition parameters is determined, which ensure...
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| Zitieren: | Structure of polycrystalline diamond coatings deposited by СVD method in the plasma of glow discharge with the use of pulse power supply / K.I. Koshevoy, Yu.Ya. Volkov, V.E. Strel’nitskij, E.N. Reshetnyak // Problems of Atomic Science and Technology. — 2021. — № 2. — С. 113-118. — Бібліогр.: 22 назв. — англ. |
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irk-123456789-1949572023-12-01T21:03:59Z Structure of polycrystalline diamond coatings deposited by СVD method in the plasma of glow discharge with the use of pulse power supply Koshevoy, K.I. Volkov, Yu.Ya. Strel’nitskij, V.E. Reshetnyak, E.N. Physics of radiation and ion-plasma technologies The structure of CVD carbon coatings synthesized in a hydrogen-methane mixture in the plasma of a glow discharge stabilized by a magnetic field using a pulsed power supply was studied by X-ray diffraction analysis and optical microscopy. The range of deposition parameters is determined, which ensure formation of polycrystalline diamond coatings. The coatings consist of diamond crystals with a clearly defined cut and the crystal lattice parameter close to the tabular value for natural diamond. The influence of the methane partial pressure in the gas mixture and the substrate temperature on the size and predominant orientation of diamond crystals in the coatings was determined. It is established that the use of the pulse mode and grounding of the substrate holder helps to improve the quality of diamond coatings. Методами рентгеноструктурного аналізу та оптичної мікроскопії досліджено структуру CVD вуглецевих покриттів, що синтезуються у воднево-метановій суміші в плазмі тліючого розряду, стабілізованого магнітним полем, із застосуванням імпульсного джерела живлення. Визначено діапазон параметрів осадження, що забезпечують формування полікристалічних алмазних покриттів, які складаються з алмазних кристалів з чітко вираженою огранкою та параметром кристалічної решітки, близьким до табличної величини для природного алмазу. З’ясовано впливи парціального тиску метану в газовій суміші і температури підкладки на розмір та переважну орієнтацію кристалів алмазу в покриттях. Встановлено, що застосування імпульсного режиму та заземлення підкладинкотримача сприяє покрашенню якості покриттів. Методами рентгеноструктурного анализа и оптической микроскопии исследована структура CVD углеродных покрытий, синтезируемых в водородно-метановой смеси в плазме тлеющего разряда, стабилизированного магнитным полем, с применением импульсного источника питания. Определен диапазон параметров осаждения, обеспечивающих формирование поликристаллических алмазных покрытий, состоящих из алмазных кристаллов с четко выраженной огранкой и параметром кристаллической решетки, близким к табличному значению для природного алмаза. Выяснено влияние парциального давления метана в газовой смеси и температуры подложки на размер и преимущественную ориентацию кристаллов алмаза в покрытиях. Установлено, что использование импульсного режима и заземленного подложкодержателя способствует улучшению качества покрытий. 2021 Article Structure of polycrystalline diamond coatings deposited by СVD method in the plasma of glow discharge with the use of pulse power supply / K.I. Koshevoy, Yu.Ya. Volkov, V.E. Strel’nitskij, E.N. Reshetnyak // Problems of Atomic Science and Technology. — 2021. — № 2. — С. 113-118. — Бібліогр.: 22 назв. — англ. 1562-6016 DOI: https://doi.org/10.46813/2021-132-113 http://dspace.nbuv.gov.ua/handle/123456789/194957 537.534.2:679.826 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Physics of radiation and ion-plasma technologies Physics of radiation and ion-plasma technologies |
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Physics of radiation and ion-plasma technologies Physics of radiation and ion-plasma technologies Koshevoy, K.I. Volkov, Yu.Ya. Strel’nitskij, V.E. Reshetnyak, E.N. Structure of polycrystalline diamond coatings deposited by СVD method in the plasma of glow discharge with the use of pulse power supply Вопросы атомной науки и техники |
| description |
The structure of CVD carbon coatings synthesized in a hydrogen-methane mixture in the plasma of a glow discharge stabilized by a magnetic field using a pulsed power supply was studied by X-ray diffraction analysis and optical microscopy. The range of deposition parameters is determined, which ensure formation of polycrystalline diamond coatings. The coatings consist of diamond crystals with a clearly defined cut and the crystal lattice parameter close to the tabular value for natural diamond. The influence of the methane partial pressure in the gas mixture and the substrate temperature on the size and predominant orientation of diamond crystals in the coatings was determined. It is established that the use of the pulse mode and grounding of the substrate holder helps to improve the quality of diamond coatings. |
| format |
Article |
| author |
Koshevoy, K.I. Volkov, Yu.Ya. Strel’nitskij, V.E. Reshetnyak, E.N. |
| author_facet |
Koshevoy, K.I. Volkov, Yu.Ya. Strel’nitskij, V.E. Reshetnyak, E.N. |
| author_sort |
Koshevoy, K.I. |
| title |
Structure of polycrystalline diamond coatings deposited by СVD method in the plasma of glow discharge with the use of pulse power supply |
| title_short |
Structure of polycrystalline diamond coatings deposited by СVD method in the plasma of glow discharge with the use of pulse power supply |
| title_full |
Structure of polycrystalline diamond coatings deposited by СVD method in the plasma of glow discharge with the use of pulse power supply |
| title_fullStr |
Structure of polycrystalline diamond coatings deposited by СVD method in the plasma of glow discharge with the use of pulse power supply |
| title_full_unstemmed |
Structure of polycrystalline diamond coatings deposited by СVD method in the plasma of glow discharge with the use of pulse power supply |
| title_sort |
structure of polycrystalline diamond coatings deposited by сvd method in the plasma of glow discharge with the use of pulse power supply |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2021 |
| topic_facet |
Physics of radiation and ion-plasma technologies |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/194957 |
| citation_txt |
Structure of polycrystalline diamond coatings deposited by СVD method in the plasma of glow discharge with the use of pulse power supply / K.I. Koshevoy, Yu.Ya. Volkov, V.E. Strel’nitskij, E.N. Reshetnyak // Problems of Atomic Science and Technology. — 2021. — № 2. — С. 113-118. — Бібліогр.: 22 назв. — англ. |
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Вопросы атомной науки и техники |
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| fulltext |
ISSN 1562-6016. ВАНТ. 2021. №2(132) 113
https://doi.org/10.46813/2021-132-113
UDC 537.534.2:679.826
STRUCTURE OF POLYCRYSTALLINE DIAMOND COATINGS
DEPOSITED BY СVD METHOD IN THE PLASMA OF GLOW
DISCHARGE WITH THE USE OF PULSE POWER SUPPLY
K.I. Koshevoy, Yu.Ya. Volkov, V.E. Strel’nitskij, E.N. Reshetnyak
National Science Center ”Kharkov Institute of Physics and Technology”,
Kharkiv, Ukraine
E-mail: strelnitskij@kipt.kharkov.ua
The structure of CVD carbon coatings synthesized in a hydrogen-methane mixture in the plasma of a glow
discharge stabilized by a magnetic field using a pulsed power supply was studied by X-ray diffraction analysis and
optical microscopy. The range of deposition parameters is determined, which ensure formation of polycrystalline
diamond coatings. The coatings consist of diamond crystals with a clearly defined cut and the crystal lattice
parameter close to the tabular value for natural diamond. The influence of the methane partial pressure in the gas
mixture and the substrate temperature on the size and predominant orientation of diamond crystals in the coatings
was determined. It is established that the use of the pulse mode and grounding of the substrate holder helps to
improve the quality of diamond coatings.
INTRODUCTION
Diamond deposited by Chemical Vapor Deposition
(CVD) covers a wide range of synthetic diamond
materials with a wide variety of properties such as high
hardness, elasticity modulus, thermal conductivity, low
friction coefficient, significant range of changes in
electrical characteristics, chemical inertness,
biocompatibility, thermal and radiation resistance.
Polycrystalline diamond in the form of thin films and
coatings is becoming increasingly popular in
electronics, mechanical engineering, chemical
production, optics, nuclear power, medicine and other
fields of science and technology, including for hard
applications involving extreme high speeds, loads,
temperatures and aggressive environment [1–3].
In the CVD process diamond is synthesized from a
gas mixture of hydrogen and hydrocarbon (usually
methane) in the region of thermodynamic stability of
graphite. Atomic hydrogen and methyl radicals play a
key role in the growth of diamond. For their formation it
is necessary to activate the gas mixture. In the first
successful experiments of diamond growth, this was
achieved by the method of hot filament – heating the
gas with tungsten wire [1]. Since then, many methods of
activating the gas mixture using microwave plasma, arc
plasmatrons, glow discharge, etc. have been developed
and improved. The main parameters that determine the
process of CVD diamond are: gas mixture pressure,
excitation power (which determines the gas
temperature), the proportion of hydrocarbons in the gas
mixture and the substrate temperature. Each method of
activation has both advantages and disadvantages.
Further development of industrial synthesis
technologies is aimed at ensuring the best price/quality
ratio by increasing the growth rate of diamond films and
deposition area, reducing the energy consumption of the
process and gas consumption, as well as achieving
stability and reproducibility of the synthesis process.
First of all the main directions of research are connected
with improvement of systems of plasma excitation and
their power supplies, and also with increase the general
power of the equipment [3].
Currently, for the activation of the working gas is
most often used microwave discharge, for the
implementation of which requires quite expensive and
complex equipment. Significantly simplify and reduce
the cost of the synthesis method allows the use of a
glow discharge to excite the gas mixture. In this case,
the substrate for the CVD diamond is located on the
anode, to which an electric potential is applied relative
to the cathode. The area of the growing diamond film is
limited by the size of the electrodes and the power of
the electric supplies [4–6].
In Ukraine work on the synthesis of diamond
coatings is carried out at the National Science Center
“Kharkоv Institute of Physics and Technology”, where
the original equipment and deposition method of
polycrystalline diamond coatings by DC glow
discharge, stabilized by a transverse magnetic field have
been developed [7–12]. The rotation of the current
channel in a magnetic field allows to provide a high
current density (more than 1 A/cm
2
) and makes it
possible to deposit the diamond coatings with a
thickness in the range from several to hundreds microns
on a fairly large area. The work to upgrade existing
equipment has been carried out last years. The design of
the anode was changed and its grounding was
implemented in order to eliminate the presence of a
negative floating potential on the substrate holder,
which in the previous design reached several hundred
volts. High potential can have a negative effect on the
deposition rate of coatings and their quality. The
geometric dimensions and location of the electrodes are
optimized to ensure the stability of the discharge
combustion. It is shown that due to the change of the
constructive scheme of activation of the gaseous
medium the synthesis of diamond films with high
characteristics can be carried out with a significant
reduction of energy consumption [13, 14].
The next stage of work to increase the productivity
of the method was the replacement of the DC power
mailto:strelnitskij@kipt.kharkov.ua
114 ISSN 1562-6016. ВАНТ. 2021. №2(132)
supply for the excitation of the glow discharge on pulse
one. According to the literature, the use of pulsed power
supplies to excite microwave plasma leads to an
increase in the growth rate of diamond coatings without
increasing the average discharge power [15] while
maintaining the quality of the coatings. In [16] we
showed that in the case of excitation of a gas
environment by a glow discharge, a similar effect can be
obtained in terms of increasing the coatings growth rate,
however, the structure of the coatings requires more
careful study.
The aim of this work was to study the effect of
deposition parameters on the structure of polycrystalline
diamond coatings synthesized on upgraded equipment
by the CVD method in the glow discharge plasma using
a pulse power supply.
RESEARCH METHODOLOGY
CVD diamond coatings were deposited in a glow
discharge stabilized by a magnetic field in a mixture of
H2 and CH4 on the equipment described in [7–9]. In
these studies, a combined disc cathode Ø 115 mm and a
substrate holder Ø 52 mm were used. The DC power
source was replaced by a pulse power supply Tru
Plasma Bios 4018. The parameters of the power supply
during the coatings deposition were the follows:
frequency of 50 kHz; duty cycle of 1.1. The use of pulse
power supply has shown that the stability of the
discharge compared to DC mode is much higher. This
allows increasing the average power supplied to the
discharge without the risk of the glow discharge
compression or its transition to the arc. In these
experiments, the average power was of 2.5…3.0 kW at
a glow discharge current of 3.5…4.5 A. As substrates
were used plates of monocrystalline silicon with an
orientation (111) and dimensions of 7.0×7.0×0.5 mm.
To enhance the crystals nucleation before coating
deposition, the substrate surface was subjected to
machining with diamond powder ACM 2/3. The coating
was deposited at different CH4 content in the hydrogen-
methane mixture in the range of 1.5…3.0% and two
values of total pressure – 16·10
3
and 21∙10
3
Pa. Thus,
the partial pressure of CH4 in the vacuum chamber was
in the range of (3.2…4.8)∙10
2
Pa. The temperature of the
samples during the coating deposition, which varied in
the range of 955…1160 °C, was measured with an
optical pyrometer ”Promin”. The total deposition time
of the coatings is 8…9 h. The thickness of the coatings,
which was determined by the increase in mass per unit
area of the substrate, was in the range of 20…30 μm at a
gas pressure in the chamber of 16∙10
3
Pa and
30…40 μm at a pressure of 21∙10
3
Pa.
The study of the phase composition, texture and
substructure of coatings was performed by X-ray
diffraction analysis. Diffractograms were taken on a
DRON-3 apparatus in filtered radiation from a copper
anode in a Bragg-Brentano focusing scheme -2. The
average size of the coherent scattering regions (CSR) of
diamond in the films was determined by the Selyakov-
Scherrer formula based on the expansion of the
diffraction line (111) of diamond, taking into account
the expansion of the standard. Texture analysis was
performed by calculating texture coefficients from the
ratio:
( ) ( ) ( ) ( )
0 0/ / / ,hkl hkl hkl hkl
C m mT nI I I I
where Im
(hkl)
is the integral reflection intensity (hkl);
I0
(hkl)
– value of reflection intensity (hkl) for non-
textured powder material; n is the number of reflected
reflections.
The morphology of the surface of diamond coatings
was examined using an optical microscope MET-1.
RESULTS AND DISCUSSIONS
According to the results of X-ray diffractometry in
the synthesized coatings in the selected range of
deposition parameters (regardless of the pressure,
composition of the gas phase and substrate temperature)
a polycrystalline diamond (cubic space group Fm3m)
was formed. No other phases were detected, including
signs of crystalline or amorphous graphite. These data
are confirmed by characteristic microscopic images of
the coating surface, which show only diamond crystals
with a well-defined faceting and sizes in the range of
5…20 μm. It is determined that the coatings structure
obtained using a pulse power supply is similar to the
structure of diamond films obtained by DC glow
discharge [11–13]. The diffraction pattern of one of the
samples is shown in Fig. 1. The diamond lines are
intense, narrow, and each is represented by two doublet
lines К1 and К2 (see Fig. 1,b). The selection of the
doublet showed that the diamond lines are quite
symmetrical (see Fig. 1,c), which indicates the absence
of a significant number of defects in the crystal
structure.
40 60 80 100 120 140
I
,
a
rb
.u
n
it
s
(3
3
1
)
(4
0
0
)
(3
1
1
)
(2
2
0
)
2 , degree
(1
1
1
)
a
74,5 75,0 75,5 76,0
K
K
I
,
a
rb
.u
n
it
s
2 , degree
74,5 75,0 75,5 76,0
I
,
a
rb
.u
n
it
s
2 , degree
K
b c
Fig. 1. X-ray diffraction pattern of diamond coating (a)
deposited under partial CH4 pressure of 3.2·10
2 Pa and
substrate temperature of 1130 °C. Reflection (220)
before (b) and after (c) the selection of the doublet
ISSN 1562-6016. ВАНТ. 2021. №2(132) 115
According to the angular position of the diffraction
lines, the parameter of the crystal lattice of diamond in
the coatings was calculated. The obtained values were
in the range of 0.3565…0.3566 nm, which is close to
the tabular value for natural diamond (a = 0.35667 nm)
[17]. The obtained data indicate high crystallinity and
purity of the synthesized polycrystalline diamond
coatings.
The results of calculations of the CSR size of
diamond in the coatings are shown in Fig. 2. It is seen
that the size of CSR is in the range of 38…240 nm. As
the temperature of the substrate increases during
deposition, the size of the CSR increases nonlinearly. In
films deposited at a pressure of 21∙10
3
Pa and the lowest
content of CH4 in a hydrogen-methane mixture of 1.5%
the size of the CSR is approximately 1.5 times greater
than at a CH4 content of 2%. Similar dependences are
observed at a pressure of 16∙10
3
Pa. With an increase in
methane content from 2 to 3% the size of the CSR
decreases almost 2 times. The generalization of the
results allowed us to establish that the experimental
points in Fig. 2 fit well on the common curves of the
CSR size on the deposition temperature for fixed values
of the partial pressure CH4, i.e. at a certain carbon
content in the gas. The greatest sizes of diamond CSR
from 100 to 240 nm are observed at the lowest partial
pressure of methane 3.2∙10
2
Pa.
950 1000 1050 1100 1150
0
50
100
150
200
250
Substrate temperature, °C
4
3
2
C
S
R
s
iz
e
,
n
m
21 kPa, CH
4
- 2 %
21 kPa, CH
4
- 1,5 %
16 kPa, CH
4
- 2 %
16 kPa, CH
4
- 2,5 %
16 kPa, CH
4
- 3 %
1
Fig. 2. Dependences of size of diamond CSR on
deposition temperature for various values of partial
pressure CH4:
1 – 3.2·10
2
Pa; 2 – 4.0·10
2
Pa;
3 – 4.2·10
2
Pa; 4 – 4.8·10
2
Pa
All diamond lines are present on the diffraction
patterns of the samples, but the ratio of line intensities
differs from the values characteristic of non-textured
material. With the chaotic orientation of the crystals the
intensity of diffraction for the reflections (220) and
(400) is much lower than (111). For most deposited
coatings this ratio are not met. The analysis of the
texture of diamond coatings was performed by
calculating the texture coefficients. The texture
coefficient characterizes how many times the
probability of coincidence of the normal to the surface
of the sample with the normal to the plane (hkl) in the
investigated sample differs from that of the chaotic
distribution of grains in the non-textured sample.
It is established that the predominant orientation of
diamond crystal grains in coatings is significantly
influenced by both the synthesis temperature and the
pressure and composition of the gas phase. The results
of the calculations are summarized in Fig. 3, which
shows a map of modes that determine the texture of the
coatings. Here is the abscissa in Fig. 3 – partial pressure
of methane, the ordinate is the temperature of the
substrate. Four zones of modes are marked with solid
lines on the map. Within each area the coatings have a
similar predominant orientation. The figure for each
zone shows a typical distribution of texture coefficients.
The largest is zone 1, which in the region of low
temperatures extends over the entire investigated range
of methane pressure and has a rather complex shape.
For samples of this zone, the value of the texture
coefficient for reflection (400) significantly prevails
over the others, ie most diamond crystallites are
oriented by the axis of type 100 in the direction
normal to the film surface. This texture is most
pronounced in coatings deposited at a partial pressure of
methane of 4.2·10
3
Pa and a substrate temperature of
980 and of 1098 °C (the area is highlighted by a dashed
line in Fig. 3). The morphology of the film surface with
this texture indicates that the coating is dominated by
crystals with square facets (Fig. 4,a).
An increase in the substrate temperature, regardless
of the pressure and methane content during synthesis,
leads to a gradual decrease in the textural coefficient for
reflection (400) and an increase in the coefficients for
other reflections. In zone 2, which corresponds to a
partial pressure of (3.2…4)·10
2
Pa and a temperature
within 1050…1160 °C the coefficient for reflection
(111) predominates. The textural axis in coating
changed on 111. Crystals with triangular facets
predominate on the coating surface (see Fig. 4,b). A
further increase in temperature leads to an increase in
the texture coefficient for reflection (220), i.e. in the
samples the location of diamond grains with the axis
110 in the direction normal to the surface of the
sample – zone 3 slightly increases. With an increase in
the partial pressure of methane to 4.8·10
2
Pa and the
synthesis temperature above 1000 °C diamond grains in
the coatings are distributed almost chaotically – zone 4.
Thus by changing the partial pressure of methane in
the hydrogen-methane mixture and the temperature of
the substrate, you can adjust the size of the crystallites
and the texture in the diamond coatings. To ensure the
texture of the coatings with the axis 100, the
deposition temperature should be reduced below
1000 °C. Increasing the partial pressure of methane to
4.8·10
2
Pa leads to a more chaotic distribution of
diamond grain orientations. To ensure the maximum
size of the crystallites, the optimal partial pressure of
methane is 3.2·10
2
Pa and the substrate temperature is
about 1150 °C.
It should be noted that the results of the experiments
are in good agreement with the existing ideas about the
mechanisms of growth of polycrystalline diamond
coatings and previously obtained data.
116 ISSN 1562-6016. ВАНТ. 2021. №2(132)
3,0 3,5 4,0 4,5 5,0
950
1000
1050
1100
1150
0
1
2
3
4
5
T
(h
k
l)
(1
1
1
)
(2
2
0
)
(3
1
1
)
(4
0
0
) (3
3
1
)
0
1
2
3
4
5
T
(h
k
l) (1
1
1
)
(2
2
0
)
(3
1
1
)
(4
0
0
)
(3
3
1
)
0
1
2
3
4
5
T
(h
k
l)
(1
1
1
)
(2
2
0
)
(3
1
1
)
(4
0
0
)
(3
3
1
)
0
1
2
3
4
5
T
(h
k
l)
(1
1
1
)
(2
2
0
)
(3
1
1
)
(4
0
0
)
(3
3
1
)
0
1
2
3
4
5
T
(h
k
l)
(1
1
1
)
(2
2
0
)
(3
1
1
)
(4
0
0
)
(3
3
1
)
S
u
b
s
tr
a
te
t
e
m
p
e
ra
tu
re
,
°C
4
3
2
1
CH
4
partial pressure , 10
2
Pa
Fig. 3. Map of modes that determine the texture in diamond coatings. A typical distribution of texture coefficients is
given for each zone. Axis of predominant orientation of diamond crystallites:
zone 1 – 100; zone 2 – 111; zone 3 – 110; zone 4 – chaotic orientation
а
b
Fig. 4. Microscopic images of the surface of diamond
coatings with different textures: a – texture with an axis
100, dominated crystals with square facets;
b – texture with an axis 111, dominated crystals with
triangular facets
It is known that the structure of the diamond film is
determined by the density of the centers of diamond
nucleation and growth time. The diamond nuclei formed
on the substrate grow and close in CVD processes.
After conjunction of the crystallites, the growth of the
polycrystalline film occurs according to the model of
competitive growth of grains by Van der Drift. The
orientation of small diamond grains before conjunction
is almost random. After conjunction the crystals the
orientation of the individual grains becomes more
regular. The crystals with the highest growth continue to
grow due to less favorably oriented crystals. As it grows
a limited number of crystallites survive, which lead to
the formation of sufficiently dense columnar highly
textured films. As the film thickness increases, the grain
size and the degree of texture perfection increase
slightly [18].
Wild and co-authors [19] introduced the growth
parameter α, which shows the ratio the growth rates
(Vuvw) along different axes of crystals: α = 3
1/2
V100/V111.
The equilibrium shape of the crystal is determined by
the faces with the lowest growth rate. The direction
111 will increase the fastest when α is 1 and the
growth morphology is cubic. When α is 3, the fastest
growing direction will be 100, and the growth
morphology will be an octahedron. In intermediate
cases, the shape of the crystals will be more complex. In
practice, it is determined that the main influence on the
morphology of the films and the corresponding
parameter α have the substrate temperature and the
concentration of hydrocarbons in the gas mixture. Some
works provide maps of modes that determine the values
of the parameters α or surface morphology [20, 21]. We
believe that the map of the distribution of texture
coefficients, which is shown in Fig. 3 is more
informative. It is clear that for each of the methods of
CVD synthesis of diamond coatings, the distribution of
zones on the maps will be significantly different. Thus
in coatings deposited using gas excitation by the hot
filament method chaotic grain orientation is often
present. Samples grown in high density plasma
conditions (e.g. using microwave excitation) are usually
more textured [22].
ISSN 1562-6016. ВАНТ. 2021. №2(132) 117
The authors of [5], who synthesized the coating
using a glow discharge, noted that the change in the
morphology and orientation of diamond crystals in the
coatings affects the rate of their deposition. According
to their data, with the increase of methane content from
0.9…1.2 to 5%, the predominant orientation changes
between 100 and 110, and when reaching 7% the
orientation becomes chaotic. The coatings with
orientation 110, obtained at a methane content of 4%,
have a maximum deposition rate. Unfortunately, the
authors did not control the temperature of the substrates
during deposition. In our experiments, the increase in
methane content leads to an increase in the coatings
deposition rate, the stronger the higher the substrate
temperature [16]. At the same time, at fixed methane
content the dependence of the deposition rate on
temperature has a maximum, similar to the data of [5].
We did not find unambiguous correlations between the
texture in the coatings and the rate of their deposition
It was shown previously that the average diamond
grain size in coatings deposited on diamond powder-
treated substrates using DC glow discharge is
determined by the density of diamond nucleus and is
virtually independent of the deposition temperature
[11]. On the contrary, the size of the CSR determined by
the X-ray method increases exponentially with
increasing temperature. In addition, in contrast to the
increase in diamond grain sizes the value of CSR does
not change with the thickness of the coatings. Areas of
coherent scattering are blocks in the volume of a crystal
grain with a sufficiently perfect crystal structure, which
are separated by small-angle boundaries. The presence
of small-angle boundaries formed by dislocation walls
can adversely affect many properties of the material,
primarily mechanical, electrical and optical. It is shown
that the size of CSR is determined by the ability of
dislocations formed in the volume of grains to move,
lining up in the dislocation walls, which increases with
temperature. In this work, when using the pulse power
supply, we obtained similar dependences of the growth
of the size of the CSR on the temperature. However, the
values of CSR size in 3 times higher, i.e. diamond
grains are more perfect. Another factor contributing to
the improvement of grain perfection is the grounding of
the substrate holder on the upgraded version of the
equipment. In the previous version of equipment, the
presence of a high floating potential on the insulated
substrate holder led to the bombardment of the
condensation surface by accelerated ions, which
contributed to the formation of structural defects in the
crystal lattice of the diamond. Thus, the advantage of
using upgraded equipment is not only to increase the
growth rate of diamond coatings, but also the ability to
improve their quality.
CONCLUSIONS
The structure of carbon coatings synthesized by the
CVD method in a hydrogen-methane mixture in the
glow discharge plasma stabilized by a magnetic field
using a pulsed power supply has been studied.
It was found that at a partial pressure of methane in
the range of (3.2…4.8)·10
2
Pа and substrate temperature
from 955 to 1160 °C coatings consist of diamond
crystals up to 20 μm with well-defined faceting and the
crystal lattice parameter closed to the table value for
natural diamond. In most coatings, a texture with a
predominant arrangement of diamond grains with an
axis 110, 111 or 100 in the direction normal to the
surface of the sample was detected. It is shown that by
changing the partial pressure of methane in the
hydrogen-methane mixture and the temperature of the
substrate, it is possible to adjust the size of the CSR and
the texture in the coatings. As the temperature increases,
the size of the CSR of the diamond increases
nonlinearly, and with increasing partial pressure of
methane decreases.
It was proposed the map of coatings deposition
modes which showing the texture depending on the
synthesis parameters.
The structure of coatings obtained using a pulse
power supply to excite a glow discharge is generally
similar to the structure of coatings synthesized in the
DC glow discharge.
It was shown that the use of pulsed mode and
grounding of the substrate holder improves the
perfection of diamond coating.
REFERENCES
1. M. Prelas, G. Popovici, L. Bigelow. Handbook of
industrial diamonds and diamond films. New York:
Marcel Dekker, 1998, 1232 р.
2. R.S. Balmer, J.R. Brandon, S.L. Clewes, et al.
Chemical vapour deposition synthetic diamond:
materials, technology and applications // J. Phys.
Condens. Matter. 2009, v. 21, N 36, р. 364221.
3. M. Schwander, K. Partes. A review of diamond
synthesis by CVD processes // Diamond and Related
Materials. 2011, N 20, p. 1287-1301.
4. K. Suzuki, A. Sawabe, H. Yasuda, et al. Growth
of diamond thin films by dc plasma chemical vapor
deposition // Appl. Phys. Lett. 1987, N 50, р. 728-729.
5. P. Hartmann, R. Haubner, B. Lux Deposition of
thick diamond films by pulsed d.c. glow discharge CVD
// Diamond and Related Materials. 1996, N 5, р. 850-
856.
6. S. Sciortino, S. Lagomarsinoa, F. Pieralli, et al.
Polycrystalline diamond synthesis by means of high
power pulsed plasma glow discharge CVD // Diamond
and Related Materials. 2002, N 11, р. 573-578.
7. O.A. Opalev, V.K. Pashnev, I.K. Kovalchuk, et
al. Synthesis of diamond coatings in a glow discharge
stabilized by a magnetic field // Problems of Atomic
Science and Technology. 2000, N 4, p 158-164.
8. V.K. Pashnev, O.A. Opalev, V.I. Grytsyna, et al.
Deposition of diamond coatings using a glow discharge
stabilized by a magnetic field // Physical Surface
Engineering. 2003, v. 1, N 1, p. 49-55.
9. V.K. Pashnev, V.E. Strel’nitskij, O.A. Opalev, et
al. Influence of a Transverse Magnetic Field on the
Characteristics of a DC Gas Discharge // Plasma
Physics Reports. 2004. v. 30, N 9, р. 15-20.
10. I.I. Vyrovets, V.I. Gritsyna, S.F. Dudnik, et al.
X-ray diffraction study of the structure and stress state
of diamond coatings obtained in a glow discharge //
Problems of Atomic Science and Technology. 2008, N 1,
p. 142-146.
118 ISSN 1562-6016. ВАНТ. 2021. №2(132)
11. I.I. Vyrovets, V.I. Gritsyna, O.A. Opalev, et al.
Using micro- and nanodispersive diamond for
deposition of polycrystalline diamond films in glow
discharge // Physical Surface Engineering. 2007, v. 5,
N 1-2, p. 87-93
12. I.I. Vyrovets, V.I. Grytsyna, S.F. Dudnik, et al.
Surface morphology and structure of nanocrystalline
diamond films deposited in CH4/H2/Ar glow discharge
plasma // Functional Materials. 2009, v. 16, N 2,
p. 155-160.
13. V.I. Gritsyna, S.F. Dudnik, O.A. Opalev,
V.Е. Strel’nitskij. Using DC glow discharge for
diamond coatings synthesis // Problems of Atomic
Science and Technology. 2018, N 1, p. 93-95.
14. V.I. Gritsyna, S.F. Dudnik, O.A. Opalev, et al.
Peculiarities of diamond film synthesis by the glow
discharge // Problems of Atomic Science and
Technology. 2018, N 1, p. 96-100.
15. A.B. Muchnikov, A.L. Vikharev, A.M. Gor-
bachev, D.B. Radishev. Comparative study of
homoepitaxial single crystal diamond growth at
continuous and pulsed mode of MPACVD reactor
operation // Diamond and Related Materials, 2011,
v. 20, N 8, р. 1225-1228.
16. K.I. Koshevoy, Y.Ya. Volkov, V.E. Strel’nit-
skij, E.N. Reshetnyak. Application of pulse power
supply for diamond coatings deposition in glow
discharge plasma // Problems of Atomic Science and
Technology. 2019, N 1, p. 197-200.
17. J. Singh. Physics of semiconductors and their
heterostructures. New York: McGraw-Hill, 1993,
864 р.
18. Van der Drift A. Evolutionary selection, a
principle governing growth orientation in vapour-
deposited layers // Philips Res. Rep. 1967, N 22,
р. 267-288.
19. C. Wild, R. Kohl, N. Herres, et al. Oriented
CVD diamond films: twin formation, structure and
morphology // Diamond and Related Materials. 1994,
v. 3, p. 373-381.
20. Y. Yokota, Y. Ando, K. Kobashi, et al.
Morphology control of diamond films in the region of
α=1–1.5 using a 60-kW microwave plasma CVD reactor
// Diamond and Related Materials. 2003, N 12,
p. 295-297.
21. R. Tu, T. Xu, D. Li, S. Zhang, et al.
Morphology and Mechanical Behavior of Diamond
Films Fabricated by IH-MPCVD // RSC Adv.
2018, N 8, р. 16061-16068.
22. T. Teraji, T. Taniguchi, S. Koizumi, et al.
Chemical vapor deposition of 12C isotopically enriched
Polycrystalline diamond // Jpn. J. Appl. Phys. 2012,
N 51, р. 090104 (1–7).
Статья поступила в редакцию 25.02.2021 г.
СТРУКТУРА ПОЛИКРИСТАЛЛИЧЕСКИХ АЛМАЗНЫХ ПОКРЫТИЙ,
ОСАЖДЕННЫХ МЕТОДОМ СVD В ПЛАЗМЕ ТЛЕЮЩЕГО РАЗРЯДА,
С ИСПОЛЬЗОВАНИЕМ ИМПУЛЬСНОГО ИСТОЧНИКА ПИТАНИЯ
К.И. Кошевой, Ю.Я. Волков, В.Е. Стрельницкий, Е.Н. Решетняк
Методами рентгеноструктурного анализа и оптической микроскопии исследована структура CVD
углеродных покрытий, синтезируемых в водородно-метановой смеси в плазме тлеющего разряда,
стабилизированного магнитным полем, с применением импульсного источника питания. Определен
диапазон параметров осаждения, обеспечивающих формирование поликристаллических алмазных
покрытий, состоящих из алмазных кристаллов с четко выраженной огранкой и параметром кристаллической
решетки, близким к табличному значению для природного алмаза. Выяснено влияние парциального
давления метана в газовой смеси и температуры подложки на размер и преимущественную ориентацию
кристаллов алмаза в покрытиях. Установлено, что использование импульсного режима и заземленного
подложкодержателя способствует улучшению качества покрытий.
СТРУКТУРА ПОЛІКРИСТАЛІЧНИХ АЛМАЗНИХ ПОКРИТТІВ,
ОСАДЖЕНИХ МЕТОДОМ СVD У ПЛАЗМІ ТЛІЮЧОГО РОЗРЯДУ,
ІЗ ЗАСТОСУВАННЯМ ІМПУЛЬСНОГО ДЖЕРЕЛА ЖИВЛЕННЯ
К.І. Кошевий, Ю.Я. Волков, В.Є. Стрельницький, О.М. Решетняк
Методами рентгеноструктурного аналізу та оптичної мікроскопії досліджено структуру CVD вуглецевих
покриттів, що синтезуються у воднево-метановій суміші в плазмі тліючого розряду, стабілізованого
магнітним полем, із застосуванням імпульсного джерела живлення. Визначено діапазон параметрів
осадження, що забезпечують формування полікристалічних алмазних покриттів, які складаються з алмазних
кристалів з чітко вираженою огранкою та параметром кристалічної решітки, близьким до табличної
величини для природного алмазу. З’ясовано впливи парціального тиску метану в газовій суміші і
температури підкладки на розмір та переважну орієнтацію кристалів алмазу в покриттях. Встановлено, що
застосування імпульсного режиму та заземлення підкладинкотримача сприяє покрашенню якості покриттів.
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