Influence of X-ray irradiation on the optical absorption edge and refractive index dispersion in Cu₆PS₅I-based thin films deposited using magnetron sputtering
Cu₆PS₅I-based thin films were deposited using non-reactive radio-frequency magnetron sputtering. Structural studies of thin films were performed by scanning electron microscopy, and their chemical composition was determined using energy-dispersive X-ray spectroscopy. As-deposited thin films were irr...
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| Опубліковано в: : | Semiconductor Physics Quantum Electronics & Optoelectronics |
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| Дата: | 2017 |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2017
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| Цитувати: | Influence of X-ray irradiation on the optical absorption edge and refractive index dispersion in Cu₆PS₅I-based thin films deposited using magnetron sputtering / I.P. Studenyak, M.M. Kutsyk, A.V. Bendak, V. Yu. Izai, P. Kus, M. Mikula // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2017. — Т. 20, № 2. — С. 246-249. — Бібліогр.: 12 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860271161184616448 |
|---|---|
| author | Studenyak, I.P. Kutsyk, M.M. Bendak, A.V. Izai, V.Yu. Kus, P. Mikula, M. |
| author_facet | Studenyak, I.P. Kutsyk, M.M. Bendak, A.V. Izai, V.Yu. Kus, P. Mikula, M. |
| citation_txt | Influence of X-ray irradiation on the optical absorption edge and refractive index dispersion in Cu₆PS₅I-based thin films deposited using magnetron sputtering / I.P. Studenyak, M.M. Kutsyk, A.V. Bendak, V. Yu. Izai, P. Kus, M. Mikula // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2017. — Т. 20, № 2. — С. 246-249. — Бібліогр.: 12 назв. — англ. |
| collection | DSpace DC |
| container_title | Semiconductor Physics Quantum Electronics & Optoelectronics |
| description | Cu₆PS₅I-based thin films were deposited using non-reactive radio-frequency magnetron sputtering. Structural studies of thin films were performed by scanning electron microscopy, and their chemical composition was determined using energy-dispersive X-ray spectroscopy. As-deposited thin films were irradiated with wideband radiation of a Cu-anode X-ray tube at different exposure times. Optical transmission spectra of X-ray irradiated Cu₅.₅₆P1.₆₆S₄.₉₃I₀.₈₅ thin films were measured depending on irradiation time. The Urbach absorption edge and dispersion of refractive index for X-rays irradiated Cu₅.₅₆P1.₆₆S₄.₉₃I₀.₈₅ thin films were studied. It has been revealed that the nonlinear decrease of energy pseudogap and the nonlinear increase of refractive index occur with the increase of X-ray irradiation time.
|
| first_indexed | 2026-03-21T11:33:47Z |
| format | Article |
| fulltext |
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2017. V. 20, N 2. P. 246-249.
doi: https://doi.org/10.15407/spqeo20.02.246
© 2017, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
246
PACS 78.40.Ha, 77.80.Bh
Influence of X-ray irradiation on the optical absorption edge
and refractive index dispersion in Cu6PS5I-based thin films
deposited using magnetron sputtering
I.P. Studenyak1, M.M. Kutsyk1, A.V. Bendak1, V.Yu. Izai1, P. Kúš2, M. Mikula2
1Uzhhorod National University, Faculty of Physics,
3, Narodna Sq., 88000 Uzhhorod, Ukraine
2Comenius University, Faculty of Mathematics, Physics and Informatics,
Mlynska dolina, 84248 Bratislava, Slovakia,
E-mail:studenyak@dr.com
Abstract. Cu6PS5I-based thin films were deposited using non-reactive radio-frequency
magnetron sputtering. Structural studies of thin films were performed by scanning
electron microscopy, their chemical composition were determined using energy-
dispersive X-ray spectroscopy. As-deposited thin films were irradiated with wideband
radiation of Cu-anode X-ray tube at different exposition times. Optical transmission
spectra of X-ray irradiated Cu5.56P1.66S4.93I0.85 thin films were measured depending on
irradiation time. The Urbach absorption edge and dispersion of refractive index for X-ray
irradiated Cu5.56P1.66S4.93I0.85 thin films were studied. It has been revealed the nonlinear
decrease of energy pseudogap and nonlinear increase of refractive index with increase of
X-ray irradiation time.
Keywords: thin film, magnetron sputtering, X-ray irradiation, optical absorption,
refractive index.
Manuscript received 31.01.17; revised version received 16.05.17; accepted for
publication 14.06.17; published online 18.07.17.
1. Introduction
Cu6PS5I compounds belong to an argyrodite family and
are known as highly-efficient superionic conductors [1].
They are promising materials for creating new types of
solid electrolyte batteries, ionistors, and electrochemical
sensors [2]. Optical properties (absorption, lumine-
scence, Raman scattering, refractive index dispersion) for
Cu6PS5I crystals were extensively studied in Refs. [2-4].
Cu6PS5I thin films for the first time were deposited
onto silicate glass substrates by non-reactive radio-
frequency magnetron sputtering [5]. Structural studies
show formation of a homogeneous two-dimensional
amorphous structure. No phase transitions are observed
in the temperature interval 77…300 K; however, at
470 K the film is partially destructed and detached from
the substrate. A typical Urbach bundle is observed,
temperature dependences of the energy pseudogap and
the Urbach energy are described in the Einstein model.
The influence of annealing on the optical
absorption edge parameters of Cu6PS5I thin films was
investigated in Ref. [6]. It should be noted that the
energy pseudogap decreases due to the annealing, but at
the same time the Urbach energy increases more than
30%. Optical properties of sulphur and phosphorous
implanted Cu6PS5I thin films as well as the influence of
ionic implantation on energy pseudogap, Urbach energy
and refraction indexes were studied in Ref. [7].
Electrical studies have shown that the total electric
conductivity of the Cu6PS5I-based thin films increases
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2017. V. 20, N 2. P. 246-249.
doi: https://doi.org/10.15407/spqeo20.02.246
© 2017, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
247
with increase of Cu atoms content [8]. Thus, with the Cu
content increase in the interval from Cu5.37P1.88S5.04I0.71
to Cu7.55P0.89S3.44I1.12, the electric conductivity increases
from 0.044 to 0.066 S/m. Besides, with the Cu content
increase, a red shift of the optical transmission spectra as
well as a typical Urbach bundle, explained by strong
electron-phonon interaction, are observed. It is shown
that the Urbach tail of the investigated thin films caused
by the influence of different type disordering and mainly
determined by the contribution of static structural
disordering into the film Urbach energy.
In this paper, we report on the influence of X-ray
irradiation on the optical transmission spectra, Urbach
absorption edge parameters and refractive indexes in
Cu6PS5I-based thin films.
2. Experimental
Thin films were deposited from polycrystalline Cu6PS5I
target onto a silicate glass substrate at room temperature
by using the non-reactive radio-frequency magnetron
sputtering. The structure of the deposited films was
analyzed by X-ray diffraction and scanning electron
microscopy (SEM) technique (Hitachi S-4300). The
diffraction pattern shows the films to be amorphous. The
thin film chemical composition (Cu5.56P1.66S4.93I0.85) was
determined using the energy-dispersive X-ray spectro-
scopy (EDX) studies, which enabled us to check the
chemical composition in different points of the film
surface. The deposited Cu5.56P1.66S4.93I0.85 thin film is
observed to be depleted by copper, sulphur, iodine and
enriched with phosphorous. SEM-studies of the thin
films confirm formation of a uniform two-dimensional
structure (Fig. 1).
Fig. 1. SEM image of Cu5.56P1.66S4.93I0.85 thin film.
X-ray irradiation was performed for the different
exposition times (30, 60 and 120 min) using wideband
radiation of Cu-anode X-ray tube with approximately
400 W of power applied (33 kV, 13 mA). Optical
transmission spectra of Cu6PS5I-based thin films were
studied at room temperature with MDR-3 grating
monochromator. Spectral dependences of absorption
coefficient and dispersion dependences of refractive
index of thin films were calculated using the well-known
method [9].
3. Results and discussion
Fig. 2 presents optical transmission spectra for various
irradiation times at room temperature for X-ray
irradiated Cu5.56P1.66S4.93I0.85 thin films. With irradiation
time increase, the red shift of the short-wave part of
transmission spectra and interference maxima are
observed. Spectral dependences of the absorption
coefficient at various irradiation times at room
temperature for X-ray irradiated Cu5.56P1.66S4.93I0.85 thin
films are shown in Fig. 3. In Ref. [8], it was shown that
the optical absorption edge for non-irradiated Cu6PS5I-
based thin films in the region of its exponential
behaviour is described by the Urbach rule [10]
( ) ⎥
⎦
⎤
⎢
⎣
⎡ −ν
⋅α=να
)(
exp,
U
0
0 TE
Eh
Th , (1)
where EU(T) is the Urbach energy, α0 and E0 are the
coordinates of the convergence point in the Urbach
bundle, hν and T are the photon energy and temperature,
respectively. In the X-ray irradiated Cu5.56P1.66S4.93I0.85
thin films, we also observed the Urbach behaviour of the
optical absorption edge. It should be noted that the
optical absorption edge for X-ray irradiated
Cu5.56P1.66S4.93I0.85 thin films is shifted to the long wave
region with the irradiation time increase.
Fig. 2. Optical transmission spectra of non-irradiated (1) and
X-ray irradiated Cu5.56P1.66S4.93I0.85 thin films at various
irradiation times: (2) 30, (3) 90 and (4) 210 min.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2017. V. 20, N 2. P. 246-249.
doi: https://doi.org/10.15407/spqeo20.02.246
© 2017, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
248
Fig. 3. Spectral dependences of the absorption coefficient of
non-irradiated (1) and X-ray irradiated Cu5.56P1.66S4.93I0.85 thin
films at various irradiation times: (2) 30, (3) 90 and (4)
210 min.
To characterize the absorption edge spectral
position, such parameter as the energy pseudogap α
gE
( α
gE is the energy position of the exponential absorption
edge) at a fixed absorption coefficient value α was
determined. We used the α
gE values taken at α =
104 cm−1 for thin films (Table). The observed variation
of the optical absorption edge leads to the α
gE value
decrease and EU value increase with irradiation time
increase (from 2.835 to 2.655 eV and from 249 to
404 meV, respectively). The dependences of α
gE and
UE for X-ray irradiated Cu5.56P1.66S4.93I0.85 thin films on
irradiation time are presented in Fig. 4.
It is well-known that Urbach energy EU characte-
rizes the disordering degree in the investigated system
and is described by the equation [11]
( ) ( )XT EEE UUU += , (2)
where ( )TEU and ( )XEU are the contributions of
temperature and structural disordering to EU, respecti-
vely. The Urbach energy EU increase is the evidence of
the structural disordering increase caused by X-ray
irradiation.
Table. Optical parameters of non-irradiated and X-ray
irradiated Cu5.56P1.66S4.93I0.85 thin films.
Irradiation
time (min) 0 30 90 210
n 2.443 2.450 2.455 2.461
α
gE (eV) 2.835 2.792 2.699 2.655
UE (meV) 249.3 357.5 382.1 403.6
Fig. 4. Dependences of the energy pseudogap α
gE (α =
104 cm–1) and Urbach energy EU on X-ray irradiation time for
Cu5.56P1.66S4.93I0.85 thin films.
Dispersion dependences of the refractive index for
the X-ray irradiated Cu5.56P1.66S4.93I0.85 thin films at
various irradiation time are presented in Fig. 5. In the
transparency region, a slight dispersion of the refractive
index for the X-ray irradiated Cu5.56P1.66S4.93I0.85 thin
films is observed, increasing with approaching to the
optical absorption edge. With the irradiation time
increase, the nonlinear increase of the refractive index in
the X-ray irradiated Cu5.56P1.66S4.93I0.85 thin films is
revealed (the X-ray irradiation leads to the refractive
index increase from 2.443 to 2.461 for λ = 1 µm).
It should be noted that the results of the similar
investigations of the optical properties of X-ray
irradiated a-Se1−xAsx thin films were recently presented
in Ref. [12]. It is shown that as a result of X-ray
irradiation, there is an increase in the refractive index
and a decrease in the film thickness (increase in its
density).
Fig. 5. Refractive index dispersions of non-irradiated (1) and
X-ray irradiated Cu5.56P1.66S4.93I0.85 thin films at various
irradiation times: (2) 30, (3) 90 and (4) 210 min. The inset
shows the dependence of refractive index on X-ray irradiation
time.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2017. V. 20, N 2. P. 246-249.
doi: https://doi.org/10.15407/spqeo20.02.246
© 2017, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
249
4. Conclusions
Cu5.56P1.66S4.93I0.85 thin films were deposited onto silicate
glass substrates by using the non-reactive radio-
frequency magnetron sputtering. The influence of X-ray
irradiation on optical properties of Cu5.56P1.66S4.93I0.85
thin films has been investigated. With the irradiation
time increase, the decrease of the energy pseudogap as
well as the increase of the Urbach energy and refractive
index have been observed. Thus, the X-ray irradiation
leads to the thin films darkening and density increase.
Besides, the increase of Urbach energy is the evidence of
increase in structural disordering contribution, which is
caused by X-ray irradiation.
Acknowledgements
Mykhailo Kutsyk (contract number 51602011) is deeply
grateful to the International Visegrad Fund scholarship
for the funding of the project.
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| id | nasplib_isofts_kiev_ua-123456789-214924 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1560-8034 |
| language | English |
| last_indexed | 2026-03-21T11:33:47Z |
| publishDate | 2017 |
| publisher | Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| record_format | dspace |
| spelling | Studenyak, I.P. Kutsyk, M.M. Bendak, A.V. Izai, V.Yu. Kus, P. Mikula, M. 2026-03-04T12:48:48Z 2017 Influence of X-ray irradiation on the optical absorption edge and refractive index dispersion in Cu₆PS₅I-based thin films deposited using magnetron sputtering / I.P. Studenyak, M.M. Kutsyk, A.V. Bendak, V. Yu. Izai, P. Kus, M. Mikula // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2017. — Т. 20, № 2. — С. 246-249. — Бібліогр.: 12 назв. — англ. 1560-8034 PACS: 78.40.Ha, 77.80.Bh https://nasplib.isofts.kiev.ua/handle/123456789/214924 https://doi.org/10.15407/spqeo20.02.246 Cu₆PS₅I-based thin films were deposited using non-reactive radio-frequency magnetron sputtering. Structural studies of thin films were performed by scanning electron microscopy, and their chemical composition was determined using energy-dispersive X-ray spectroscopy. As-deposited thin films were irradiated with wideband radiation of a Cu-anode X-ray tube at different exposure times. Optical transmission spectra of X-ray irradiated Cu₅.₅₆P1.₆₆S₄.₉₃I₀.₈₅ thin films were measured depending on irradiation time. The Urbach absorption edge and dispersion of refractive index for X-rays irradiated Cu₅.₅₆P1.₆₆S₄.₉₃I₀.₈₅ thin films were studied. It has been revealed that the nonlinear decrease of energy pseudogap and the nonlinear increase of refractive index occur with the increase of X-ray irradiation time. Mykhailo Kutsyk (contract number 51602011) is deeply grateful to the International Visegrad Fund scholarship for the funding of the project. en Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України Semiconductor Physics Quantum Electronics & Optoelectronics Influence of X-ray irradiation on the optical absorption edge and refractive index dispersion in Cu₆PS₅I-based thin films deposited using magnetron sputtering Article published earlier |
| spellingShingle | Influence of X-ray irradiation on the optical absorption edge and refractive index dispersion in Cu₆PS₅I-based thin films deposited using magnetron sputtering Studenyak, I.P. Kutsyk, M.M. Bendak, A.V. Izai, V.Yu. Kus, P. Mikula, M. |
| title | Influence of X-ray irradiation on the optical absorption edge and refractive index dispersion in Cu₆PS₅I-based thin films deposited using magnetron sputtering |
| title_full | Influence of X-ray irradiation on the optical absorption edge and refractive index dispersion in Cu₆PS₅I-based thin films deposited using magnetron sputtering |
| title_fullStr | Influence of X-ray irradiation on the optical absorption edge and refractive index dispersion in Cu₆PS₅I-based thin films deposited using magnetron sputtering |
| title_full_unstemmed | Influence of X-ray irradiation on the optical absorption edge and refractive index dispersion in Cu₆PS₅I-based thin films deposited using magnetron sputtering |
| title_short | Influence of X-ray irradiation on the optical absorption edge and refractive index dispersion in Cu₆PS₅I-based thin films deposited using magnetron sputtering |
| title_sort | influence of x-ray irradiation on the optical absorption edge and refractive index dispersion in cu₆ps₅i-based thin films deposited using magnetron sputtering |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/214924 |
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