Plasma treatment of titanium dioxide film for black TiO₂
The results of the treatment of TiO₂ film in volume discharge with an Ar/H₂ mixture are presented. The treated film demonstrates the changes in transparency and conductivity. Raman spectra show no changes in the phase state of the film after plasma treatment. Представлено результати обробки плівки Т...
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| Опубліковано в: : | Problems of Atomic Science and Technology |
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| Дата: | 2023 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2023
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| Цитувати: | Plasma treatment of titanium dioxide film for black TiO₂ / E.K. Frolova, V.O. Khomych, R.M. Kravchuk, O.F. Kolomys, Yu.M. Gudenko, O.S. Pylypchuk, V.I. Styopkin, A.M. Dobrovolskiy // Problems of Atomic Science and Technology. — 2023. — № 4. — С. 180-183. — Бібліогр.: 9 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860072056825053184 |
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| author | Frolova, E.K. Khomych, V.O. Kravchuk, R.M. Kolomys, O.F. Gudenko, Yu.M. Pylypchuk, O.S. Styopkin, V.I. Dobrovolskiy, A.M. |
| author_facet | Frolova, E.K. Khomych, V.O. Kravchuk, R.M. Kolomys, O.F. Gudenko, Yu.M. Pylypchuk, O.S. Styopkin, V.I. Dobrovolskiy, A.M. |
| citation_txt | Plasma treatment of titanium dioxide film for black TiO₂ / E.K. Frolova, V.O. Khomych, R.M. Kravchuk, O.F. Kolomys, Yu.M. Gudenko, O.S. Pylypchuk, V.I. Styopkin, A.M. Dobrovolskiy // Problems of Atomic Science and Technology. — 2023. — № 4. — С. 180-183. — Бібліогр.: 9 назв. — англ. |
| collection | DSpace DC |
| container_title | Problems of Atomic Science and Technology |
| description | The results of the treatment of TiO₂ film in volume discharge with an Ar/H₂ mixture are presented. The treated film demonstrates the changes in transparency and conductivity. Raman spectra show no changes in the phase state of the film after plasma treatment.
Представлено результати обробки плівки ТіО₂ в об’ємі розряду на суміші Ar/H₂. Оброблена плівка демонструє зміни в прозорості та провідності. Раманівські спектри показують відсутність змін у поліморфному стані плівки після плазмової обробки.
|
| first_indexed | 2025-12-07T17:10:57Z |
| format | Article |
| fulltext |
180 ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. № 4(146)
https://doi.org/10.46813/2023-146-180
PLASMA TREATMENT OF TITANIUM DIOXIDE FILM
FOR BLACK TiO2
E.K. Frolova
1
, V.O. Khomych
1
, R.M. Kravchuk
1
, O.F. Kolomys
2
, Yu.M. Gudenko
1
,
O.S. Pylypchuk
1
, V.I. Styopkin
1
, A.M. Dobrovolskiy
1
1
Institute of Physic NAS of Ukraine, Kyiv, Ukraine;
2
V. Lashkaryov Institute of Semiconductor Physics NASU, Kyiv, Ukraine
E-mail: dobr@iop.kiev.ua
The results of the treatment of TiO2 film in volume discharge with an Ar/H2 mixture are presented. The treated
film demonstrates the changes in transparency and conductivity. Raman spectra show no changes in the phase state
of the film after plasma treatment.
PACS: 52.77
INTRODUCTION
TiO2 is a very popular smart material in industry and
research. Titanium dioxide is popular due to its lower
price, high availability, high chemical and physical sta-
bility, non-toxicity, photochemical activity, and other
useful properties. But the wide band gap and higher
photoinduced charge recombination limit the use of
white titanium dioxide (W-TiO2) in some applications.
Today scientists are working on the reduction of the
band gap of W-TiO2, improving the absorption of visi-
ble light, and increasing conductivity. One of the ways
is the plasma treatment of W-TiO2 in the presence of H2
to make the black TiO2 (B-TiO2).
There are many types of gas discharges for the
treatment of materials for changes in their characteris-
tics. It can be the atmosphere discharges or low pres-
sure, ion-plasma beam methods, or immersive treatment
in the discharge plasma.
Now we present the preliminary results of immer-
sive plasma treatment of TiO2 films in a large-volume
discharge plasma of the low-pressure discharge with a
hollow cathode.
1. SETUP
Plasma treatment of the films was carried out at the
Institute of Physics of the National Academy of Scienc-
es of Ukraine in Kyiv. We use a large volume discharge
with a hollow cathode, Fig. 1. We can use the setup for
oxidation, nitriding, and hydrogen ion treatment of
products or materials. Now we do anatase film hydro-
genation. In our large-volume plasma generator, we
have pure argon plasma with a controlled addition of
hydrogen. The discharge has a high electron concentra-
tion and allows efficient cleaning and heating of sam-
ples. Low working pressure (1…10 Pa) allows the safe
process of parts of complex shapes before overheating
and destruction of the surface. The proposed discharge
is highly efficient for generating a large volume of
plasma with an electron concentration of
10
10
…5∙10
11
cm
-3
. The discharge allows the mainte-
nance of the optimal mode of ion cleaning, heating, and
the optimum surface temperature during processing.
The plasma generator has a hollow cathode connect-
ed to the vacuum chamber by an insulator, and the an-
nular anode at the bottom of the chamber. The sample
holder and probe were placed in the vacuum chamber.
The hollow cathode is covered with an insulator and
working gas Ar is fed through the cathode into the
chamber. This circuit protects the hot cathode from re-
active gases during usage. The cathode is a cylinder
4×35 mm from a tantalum tube.
Fig. 1. Scheme of the experimental setup:
1 vacuum chamber; 2 hollow cathode; 3 anode;
4 flat probe; 5 sample holder; 6 gauge;
7 valves; 8 controllable diaphragm
The other gas we can supply by a second line with a
separately controllable valve. So we can make different
mixtures of working gases. In the experiments, we use
H2 as additional gas. The plasma of discharge has a uni-
form profile in the central part of the chamber and de-
creases concentration by less than 20% to the chamber
wall, Fig. 2.
The TiO2 film was deposited by an electron beam
evaporating the titanium in the presence of oxygen.
Then the film was annealed to the state of anatase in a
thermal furnace at a temperature of 500°C. After the
characterization of the obtained white TiO2 film, it was
treated with plasma in immersion mode. The chamber
was pumped up to 4∙10
-1
Pa, then Ar up to 4 Pa was
ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. № 4(146) 181
supplied and a discharge with a hollow cathode was
ignited. The discharge current is 11 A and the discharge
voltage is 58 V. The sample was heated to 180°C. After
that, hydrogen was added to the chamber to a pressure
of 7 Pa, the current was 11 A, and the voltage rose to
63 V. The treatment was carried out for 30 min and the
temperature of the sample increased during this time to
300°C.
Fig. 2. The plasma concentration in the vacuum
chamber, РАr = 4 Pa
The Raman measurements were acquired in a quasi-
backscattering geometry using the Horiba Jobin-Yvon
T64000 triple spectrometer with integrated micro-
Raman setup – Olympus BX-41 microscope and Peltier-
cooled CCD detector. An excitation, 532 nm-line beam
of Spectra-Physics DPSS laser was focused by a ×50
objective (0.75 NA). The laser power was adjusted to
0.25 mW in front of the objective to ensure a good sig-
nal and to avoid any thermal effect that could trigger
structural changes.
For the optic properties investigation the Ocean Op-
tics USB2000 was used as a spectra detector in the wide
range 200…1000 nm and the DH-mini as a UV-Vis
light source. Both the absorbance and the transmittance
spectra were detected with an accuracy of 0.47 nm per
point. Absorbance spectra indicate the photon energy
absorbed by a thin layer.
2. FILM CHARACTERISTICS
We characterize the prepared films with a lot of
methods. First of all, we measure the transparency of
the hydrogenated film. The transmittance spectra were
recorded for TiO2 thin film in the wavelength range of
300 to 700 nm. Fig. 3 presents the absorption spectra of
the film. We can calculate the band gap from the ab-
sorption spectra, accordingly to Tauc’s relation as in [1].
The obtained optical band gap energy for TiO2 thin film
is 3.53 eV.
Fig. 4 presents the transmittance spectra of the film
after plasma treatment. There are two regions in the
graph: one is a strong absorption region < 330 nm and
the other one is middle transmittance region > 375 nm.
The thin film has shown nonlinear transmittance around
to 45…60% in the visible region. The originated TiO2
film has a transparency of more than 80%. After immer-
sive plasma treatment with Ar/H2 mixture, the film has a
transparency above 50%.
Also we characterize our films with Raman spec-
troscopy. Raman spectroscopy is one of the most versa-
tile and nondestructive methods used for the analysis of
structure, phase, and defects in the samples. In the case
of anatase TiO2, the group theory predicts six Raman
active modes: 3Eg +A1g+2B1g. The Eg, B1g, and A1g
phonon modes originate due to the vibrations of O-Ti-O
symmetric stretching, O-Ti-O symmetric bending, and
O-Ti-O antisymmetric stretching, respectively [2]. As
shown in Fig. 5, five characteristics modes of anatase
TiO2 (Eg(1) 151 cm
-1
, Eg(2) 202 cm
-1
, B1g 394 cm
-1
,
A1g/B1g 512 cm
-1
, and Eg(3) 634 cm
-1
) can be ob-
served in all the samples from which anatase phase of
TiO2 is confirmed. No peaks corresponding to some
additional brookite/rutile impurity phases were not de-
tected.
Fig. 3. Band gap energy of TiO2 thin film is shown
Fig. 4. Transmittance UV-Vis spectrum of TiO2 film (as-
deposited on quartz glass) is shown
100 200 300 400 500 600 700
In
te
n
s
it
y
(
a
rb
.u
n
.)
Raman shift (cm-1)
Inital
B1g
A1g/B1g Eg(3)
Eg(1)
Eg(2)
Eg(1)
w=144,7 cm-1
FWHM= 11,8 cm-1
w=148,7 cm-1
FWHM= 17,0 cm-1 Annealed
1
2
3
100 125 150 175 200
Raman shift (cm-1)
w=151,3 cm-1
FWHM= 23 cm-1 Ar+H
Fig. 5. Raman spectra of polycrystalline black TiO2 film
before (1) and under annealing (2); (3) – the Raman
spectrum of annealed black TiO2 film after argon
and hydrogen treatment. Inset shows the shift
of the main Ag (1) Raman band
182 ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. № 4(146)
For the initial black-TiO2 film the blue shift of the
main Raman band compared with reference bulk TiO2 [3]
from 143 cm
-1
to a higher wave number, 151.3 cm
-1
along with band broadening indicated the presence of
lattice disorder in black TiO2 resulting from phonon
confinement and non-stoichiometry due to the oxygen
vacancy (Vo) [4]. The presence of oxygen vacancies has
a significant impact on Ti-O vibration and the vibration-
al modes of O2
–
ions in Ti-O bond, which affects the
position, width, and intensity of the Raman bands [5].
Further thermal annealing in the air atmosphere re-
duces the oxygen vacancies, and consequently the de-
fects. As one can see in Fig. 5 (spectrum 2) annealing
leads to a reduction in the FWHM (from 23 to 11 cm
-1
),
an increase in the intensity (up to 2 times), and red shift
(from 151.3 to 144.7 cm
-1
) of the main Eg (1) Raman
mode. Furthermore, annealing also leads to an increase
in the size of the particles. According to [6], the average
size of anatase crystallites for initial and annealed films
is 5 and 15 nm, respectively.
In the Raman spectra of argon and hydrogen-treated
annealed black TiO2 (see Fig. 5, spectrum 3), the main
Eg (1) exhibited a blue shift along with peak broadening
compared to the annealed TiO2. These features were
observed earlier in the case of modified TiO2 nanoparti-
cles where non-stoichiometry and defects states were
attributed with the structure [7]. The broadening and
shifting of Raman bands have been explained by a
mechanism such as the introduction of additional de-
fects due to the incorporation of H and Ar at the bridg-
ing sites of TiO2.
The plasma treatment of the film affected the film
morphology. As can expect, the roughness of the film
decreases. Fig. 6,a,b shows SEM images of the film
surfaces before and after plasma treatment.
Fig. 6. SEM images of surfaces of initial film (a)
and treated film (b). The samples were tilted at 60º
to position normal to electron beam at SEM study
The surface of the original film is noticeably rough.
The sizes of most details of surface relief are
100…250 nm. The image of the treated film shows that
the surface is rather smooth. Most of the relief details
have sizes of 20…50 and heights of 10…20 nm.
After plasma treatment with H2 in mixture we expect
the changes in condactivity of film. We use the method
of multipoint mesurement of resistivity [8]. To study the
characteristics of electrical transport of current carriers
in the film, metal contacts were applied to it by the
method of thermal evaporation of the contact material in
a vacuum. The material of the contacts is silver. The
contact area is: 0.8 by 3 mm, and the distance between
the contacts is: 0.4, 0.7, and 0.9 mm. For the samples,
the current-current characteristics were measured at two
temperatures of 300 and 77 K. The rectangular pulses of
electric voltage with a duration of 40 μs, an amplitude
from 0 to 1000 V, and a frequency of 1 Hz were applied
to the sample. The obtained dependences of the current-
voltage characteristics at different temperatures for the
samples are presented in Fig. 7, where S1, S2, and S3
are samples with the corresponding distances between
electrical contacts of 0.4, 0.7, and 0.9 mm, respectively.
Note that the obtained I-V characteristics at 300 K
for all samples are very close to each other this is
shown in Fig. 7, which can be an additional indication
of the homogeneity of the obtained film. The value of
the specific resistance of the TiO2 film, which is deter-
mined as ρ=E/J, is related to the value obtained in the
work [9]. The difference in the size of the specific re-
sistance at 77 K for samples S1, S2, and S3 may be
caused by the influence of the reference contact on the
I-V measurement, which requires a more detailed study.
0 5 10 15 20 25
0
20
40
60
80
100
0,01 0,1 1 10
10
-2
10
-1
10
0
10
1
10
2
0 5 10 15 20 25
0,0
0,1
0,2
0,3
8
10
12
14
16
18
20
22
24
26
T = 300 K
S1
S2
S3J,
A
/c
m
2
E, kV/cm
0
1
2
3
cb
T = 77 K
S1
S2
S3
J,
A
/c
m
2
a
J,
A
/c
m
2
E, kV/cm
E, kV/cm
=
E
/J
,
kO
h
m
*c
m
Fig. 7. Experimental results are presented for two
measurement temperatures of 300 (filled colored
symbols) and 77 K (open symbols). S1, S2, and S3 are
samples with distances between electrical contacts
of 0.4, 0.7, and 0.9 mm, respectively; current-voltage
characteristics of the studied samples at different
temperatures (a); current-voltage characteristics
of the studied samples at different temperatures
in double logarithmic coordinates (b); the resistivity
dependence of the studied material (c)
It is interesting that after plasma treatment we have
the film with low resistivity, about 300 Ωcm at 300 K,
and with middle transparency, ~50%. The disadvantage
is the relatively high band gap of the film, 3.53 eV.
CONCLUSIONS
The plasma treatment of the TiO2 anatase film with
plasma of the low-pressure discharge with a hollow
cathode dose not change phase state of the film. Plasma
treatment decreases roughness of the film surface and
transparency of film. The resistivity of treated film is
about 300 Ωcm at 300 K. The homogeneity of the resis-
tivity of the treated film is high. The film has middle
transparency, ~50%, with band gap 3.53 eV.
The immersive treatment of TiO2 in plasma of the
low-pressure discharge with a hollow cathode is promis-
ing method of hydrogenenation of TiO2 films.
ISSN 1562-6016. Problems of Atomic Science and Technology. 2023. № 4(146) 183
REFERENCES
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3. G.R. Hearne et al. Effect of grain size on structural
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4. J.C. Parker, R.W. Siegel. Calibration of the Raman
spectrum to the oxygen stoichiometry of nanophase
TiO2 // Appl. Phys. Lett. 1990, v. 57, p. 943-945.
5. B. Choudhury, A. Choudhury. Ce-Nd codoping ef-
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p. 239-247.
6. Sanjeev K. Gupta, Rucha Desai, Prafulla K. Jha,
Satyaprakash Sahoo, D. Kirin. Titanium dioxide
synthesized using titaniumchloride: size effect study
using Raman spectroscopy and photoluminescence //
J. Raman Spectrosc. 2010, v. 41, p. 350-355.
7. S.M. Prokes, J.L. Gole, X. Chen, C. Burda,
W.E. Carlos. Defect-Related Optical Behavior in
Surface Modified TiO2 Nanostructures // Adv. Funct.
Mater. 2005, v. 15, № 1, p. 161-167.
8. Richard S. Waremra and Philipus Betaubun. Analy-
sis of Electrical Properties Using the four point
Probe Method // E3S W eb of Conferences. 2018,
v. 73, doi: 10.1051/e3sconf/201873 ICENIS 2018
13019 13019.
9. M. Sasikumar, N.P. Subiramaniyam. Microstructure,
electrical and humidity sensing properties of
TiO2/polyaniline nanocomposite films prepared by
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Article received 29.06.2023
ПЛАЗМОВА ОБРОБКА ДВООКИСУ ТИТАНУ ДО ЧОРНОГО ТіО2
Е.К. Фролова, В.О. Хомич, Р.М. Кравчук, О.Ф. Коломис, У.М. Гуденко,
О.С. Пилипчук, В.І. Стьопкін, А.М. Добровольський
Представлено результати обробки плівки ТіО2 в об’ємі розряду на суміші Ar/H2. Оброблена плівка де-
монструє зміни в прозорості та провідності. Раманівські спектри показують відсутність змін у поліморфно-
му стані плівки після плазмової обробки.
|
| id | nasplib_isofts_kiev_ua-123456789-196201 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T17:10:57Z |
| publishDate | 2023 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Frolova, E.K. Khomych, V.O. Kravchuk, R.M. Kolomys, O.F. Gudenko, Yu.M. Pylypchuk, O.S. Styopkin, V.I. Dobrovolskiy, A.M. 2023-12-11T12:40:55Z 2023-12-11T12:40:55Z 2023 Plasma treatment of titanium dioxide film for black TiO₂ / E.K. Frolova, V.O. Khomych, R.M. Kravchuk, O.F. Kolomys, Yu.M. Gudenko, O.S. Pylypchuk, V.I. Styopkin, A.M. Dobrovolskiy // Problems of Atomic Science and Technology. — 2023. — № 4. — С. 180-183. — Бібліогр.: 9 назв. — англ. 1562-6016 PACS: 52.77 DOI: https://doi.org/10.46813/2023-146-180 https://nasplib.isofts.kiev.ua/handle/123456789/196201 The results of the treatment of TiO₂ film in volume discharge with an Ar/H₂ mixture are presented. The treated film demonstrates the changes in transparency and conductivity. Raman spectra show no changes in the phase state of the film after plasma treatment. Представлено результати обробки плівки ТіО₂ в об’ємі розряду на суміші Ar/H₂. Оброблена плівка демонструє зміни в прозорості та провідності. Раманівські спектри показують відсутність змін у поліморфному стані плівки після плазмової обробки. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Problems of Atomic Science and Technology Applications and technologies Plasma treatment of titanium dioxide film for black TiO₂ Плазмова обробка двоокису титану до чорного TiO₂ Article published earlier |
| spellingShingle | Plasma treatment of titanium dioxide film for black TiO₂ Frolova, E.K. Khomych, V.O. Kravchuk, R.M. Kolomys, O.F. Gudenko, Yu.M. Pylypchuk, O.S. Styopkin, V.I. Dobrovolskiy, A.M. Applications and technologies |
| title | Plasma treatment of titanium dioxide film for black TiO₂ |
| title_alt | Плазмова обробка двоокису титану до чорного TiO₂ |
| title_full | Plasma treatment of titanium dioxide film for black TiO₂ |
| title_fullStr | Plasma treatment of titanium dioxide film for black TiO₂ |
| title_full_unstemmed | Plasma treatment of titanium dioxide film for black TiO₂ |
| title_short | Plasma treatment of titanium dioxide film for black TiO₂ |
| title_sort | plasma treatment of titanium dioxide film for black tio₂ |
| topic | Applications and technologies |
| topic_facet | Applications and technologies |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/196201 |
| work_keys_str_mv | AT frolovaek plasmatreatmentoftitaniumdioxidefilmforblacktio2 AT khomychvo plasmatreatmentoftitaniumdioxidefilmforblacktio2 AT kravchukrm plasmatreatmentoftitaniumdioxidefilmforblacktio2 AT kolomysof plasmatreatmentoftitaniumdioxidefilmforblacktio2 AT gudenkoyum plasmatreatmentoftitaniumdioxidefilmforblacktio2 AT pylypchukos plasmatreatmentoftitaniumdioxidefilmforblacktio2 AT styopkinvi plasmatreatmentoftitaniumdioxidefilmforblacktio2 AT dobrovolskiyam plasmatreatmentoftitaniumdioxidefilmforblacktio2 AT frolovaek plazmovaobrobkadvookisutitanudočornogotio2 AT khomychvo plazmovaobrobkadvookisutitanudočornogotio2 AT kravchukrm plazmovaobrobkadvookisutitanudočornogotio2 AT kolomysof plazmovaobrobkadvookisutitanudočornogotio2 AT gudenkoyum plazmovaobrobkadvookisutitanudočornogotio2 AT pylypchukos plazmovaobrobkadvookisutitanudočornogotio2 AT styopkinvi plazmovaobrobkadvookisutitanudočornogotio2 AT dobrovolskiyam plazmovaobrobkadvookisutitanudočornogotio2 |