Photoluminescence of As₂S₃ doped with Cr and Yb
The results of experimental researches of photoluminescence spectra in As₂S₃ glasses obtained by doping of Cr and Yb ions to As–S host matrix followed by Raman and calorimetric studies as well as low-temperature magnetization measurements have been given. Possible mechanisms of obtained effects a...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2014
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| Zitieren: | Photoluminescence of As₂S₃ doped with Cr and Yb / A.V. Stronski, O.P. Paiuk, V.V. Strelchuk, Iu.M. Nasieka, M. Vlcek // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2014. — Т. 17, № 4. — С. 341-345. — Бібліогр.: 16 назв. — англ. |
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nasplib_isofts_kiev_ua-123456789-1184202025-02-09T23:22:40Z Photoluminescence of As₂S₃ doped with Cr and Yb Stronski, A.V. Paiuk, O.P. Strelchuk, V.V. Nasieka, Iu.M. Vlček, M. The results of experimental researches of photoluminescence spectra in As₂S₃ glasses obtained by doping of Cr and Yb ions to As–S host matrix followed by Raman and calorimetric studies as well as low-temperature magnetization measurements have been given. Possible mechanisms of obtained effects are discussed. The research was supported by the project FP–7 SECURE–R21. 2014 Article Photoluminescence of As₂S₃ doped with Cr and Yb / A.V. Stronski, O.P. Paiuk, V.V. Strelchuk, Iu.M. Nasieka, M. Vlcek // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2014. — Т. 17, № 4. — С. 341-345. — Бібліогр.: 16 назв. — англ. 1560-8034 PACS 07.20.Mc, 65.60+a, 75.30.Hx, 78.30.Ly, 78.55.Qr https://nasplib.isofts.kiev.ua/handle/123456789/118420 en Semiconductor Physics Quantum Electronics & Optoelectronics application/pdf Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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English |
| description |
The results of experimental researches of photoluminescence spectra in As₂S₃
glasses obtained by doping of Cr and Yb ions to As–S host matrix followed by Raman
and calorimetric studies as well as low-temperature magnetization measurements have
been given. Possible mechanisms of obtained effects are discussed. |
| format |
Article |
| author |
Stronski, A.V. Paiuk, O.P. Strelchuk, V.V. Nasieka, Iu.M. Vlček, M. |
| spellingShingle |
Stronski, A.V. Paiuk, O.P. Strelchuk, V.V. Nasieka, Iu.M. Vlček, M. Photoluminescence of As₂S₃ doped with Cr and Yb Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Stronski, A.V. Paiuk, O.P. Strelchuk, V.V. Nasieka, Iu.M. Vlček, M. |
| author_sort |
Stronski, A.V. |
| title |
Photoluminescence of As₂S₃ doped with Cr and Yb |
| title_short |
Photoluminescence of As₂S₃ doped with Cr and Yb |
| title_full |
Photoluminescence of As₂S₃ doped with Cr and Yb |
| title_fullStr |
Photoluminescence of As₂S₃ doped with Cr and Yb |
| title_full_unstemmed |
Photoluminescence of As₂S₃ doped with Cr and Yb |
| title_sort |
photoluminescence of as₂s₃ doped with cr and yb |
| publisher |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| publishDate |
2014 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/118420 |
| citation_txt |
Photoluminescence of As₂S₃ doped with Cr and Yb / A.V. Stronski, O.P. Paiuk, V.V. Strelchuk, Iu.M. Nasieka, M. Vlcek // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2014. — Т. 17, № 4. — С. 341-345. — Бібліогр.: 16 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
| work_keys_str_mv |
AT stronskiav photoluminescenceofas2s3dopedwithcrandyb AT paiukop photoluminescenceofas2s3dopedwithcrandyb AT strelchukvv photoluminescenceofas2s3dopedwithcrandyb AT nasiekaium photoluminescenceofas2s3dopedwithcrandyb AT vlcekm photoluminescenceofas2s3dopedwithcrandyb |
| first_indexed |
2025-12-01T16:37:44Z |
| last_indexed |
2025-12-01T16:37:44Z |
| _version_ |
1850324628759642112 |
| fulltext |
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2014. V. 17, N 4. P. 341-345.
© 2014, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
341
PACS 07.20.Mc, 65.60+a, 75.30.Hx, 78.30.Ly, 78.55.Qr
Photoluminescence of As2S3 doped with Cr and Yb
A.V. Stronski1, O.P. Paiuk1, V.V. Strelchuk1, Iu.M. Nasieka1, M. Vlček2
1V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine,
41, prospect Nauky, 03028 Kyiv, Ukraine
2University of Pardubice, Faculty of Chemical Technology, Pardubice, Czech Republic
Abstract. The results of experimental researches of photoluminescence spectra in As2S3
glasses obtained by doping of Cr and Yb ions to As–S host matrix followed by Raman
and calorimetric studies as well as low-temperature magnetization measurements have
been given. Possible mechanisms of obtained effects are discussed.
Keywords: chalcogenide glass, photoluminescence, Raman spectra, thermal property,
magnetization.
Manuscript received 07.02.14; revised version received 25.06.14; accepted for
publication 29.10.14; published online 10.11.14.
1. Introduction
Chalcogenide glasses (ChGs) exhibit a number of
interesting optical properties with various potential
applications as reviewed in, for example [1, 2], etc. As
frequently pointed out by various researchers, ChGs are
promising materials for various applications because
they are transparent over a wide range of wavelengths in
the infrared region, they possess high refractive indices,
low phonon energies and are easy to fabricate.
Chalcogenide glasses can be used in applications in
sensorics, infrared optics and optoelectronics. The
glasses can be used for preparation of optical fibers both
for passive and active applications.
The refractive index and its wavelength
dependence, luminescent properties are among important
parameters that determine the suitability of materials as
optical media. The photoluminescence (PL) spectrum of
arsenic chalcogenides when excited by light with
ħω ≈ Eg (Eg is an optical bandgap energy) lies at about
half the optical gap, which means that PL undergoes a
strong Stokes shift, and it appears as a broad Gaussian-
shaped spectrum with a peak energy EPL approximately
at EPL ≈ Eg/2 [3-5]. Developments in photonics
applications highlighted the chalcogenide glass as a host
for rare-earth ions [1, 6-9].
Tanaka [10] proposed a new model for the half-gap
PL. The latter arises from recombination of electrons,
being trapped by anti-bonding states of wrong (and
strained) bonds at around the mid-gap Fermi level, and
holes in Urbach-edge states at the valence-band top. The
wrong bond seems to be the most dominant defect in
covalent chalcogenide semiconductors such as
As2S(Se)3, irrespective of glass and crystal, and
accordingly, this model can be applied to the
corresponding crystals as well. The PL fatigue, which is
more prominent in the glass, may arise from momentary
trapped electrons (type I) and broken chemical bonds
(type II) in disordered flexible lattices. However,
complete understandings of the PL fatigue remain
difficult as caused by some experimental limitations.
In this work, photoluminescence of As2S3 doped
with Cr and Yb was investigated.
2. Experimental
The glasses of compositions As2S3, As2S3:Cr 0.5 wt.%
and As2S3:Cr 0.75 wt.%, As2S3, As2S3:Yb 0.5 wt.%,
As2S3:Yb 1 wt.% and As2S3:Yb 2 wt.% were prepared
using the standard melt-quenching technique with
constituent elements of 6N purity, which were melted in
vacuum-sealed silica ampoules for 10…12 hours and
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2014. V. 17, N 4. P. 341-345.
© 2014, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
342
subsequently quenched in air. Room temperature Raman
spectra were recorded using a Fourier spectrophotometer
Bruker IFS-55 Equinox with FRA-106 attachment.
Photoluminescence of As2S3 doped with Cr was
studied within the 800…1600-nm region (T = 77 K, λex =
514 nm) using a HORIBA Jobin-Yvon T64000
spectrometer. Photoluminescence of As-S glasses
modified with Yb was excited by a laser diode at the
980-nm wavelength with the radiation intensity 150 mW
and was registered at room temperature using a Zolix
SBP 300 monochromator (resolution ~1 nm) with Zolix
CR131 attachment.
Thermal properties were studied using the DSC
technique, Tg values for undoped and doped glasses were
obtained. NETZSCH DSC 404 calorimeter (with
accuracy ±0.5 K) was used in DSC measurements.
Calorimetric measurements were carried out using
powder samples (m ~ 20 mG) in argon atmosphere under
temperature changes within 40…250 С. The heating
rate q = 10 K/min. Calibration of the calorimeter was
carried out by melting pure metals In, Sn, Bi, Pb, Al, Cu
with known values of temperature and enthalpy of
melting.
Magnetization of the samples was measured with a
Cryogenic S600 Super-conducting Quantum Interference
Device (SQUID) magnetometer within the temperature
range 5…400 K and in magnetic fields up to 5 T. A
cryogenic system was completed with automated
instrument control, data acquisition and analysis using
the National Instrument’s LabVIEW software.
3. Results
Raman spectra
Introduction of Cr impurity (Fig. 1) leads to the intensity
increase of the bands at 192, 227, 236, 1cm365 , which
correspond to the presence of non-stoichiometric
molecular fragments of the As4S4 nanophase. The
intensity of the 1cm-496 band, characteristic for the
vibrations of S-S bonds, is decreased with the Cr
introduction. The difference spectra (Fig. 2) reveal the
changes occurred in the glass structure upon variation of
composition. From these spectra, one can be see that
addition of Cr leads to intensity increase of the
1cm-150 band that corresponds to vibrations of phase-
decomposed S8 rings and the 1cm-317 band, which
can be attributed to pyramidal structural AsS3 units with
additional sulfur atoms involved into (-S-S-) chains and
joined pyramidal fragments. The main observed effect
under introduction of chromium into As2S3 is the change
of the relative concentration of the main and non-
stoichiometric structural units characteristic for As2S3
glasses.
Chalcogenide glasses As2S3 doped with ytterbium
were investigated using Raman spectroscopy to obtain
information regarding incorporation of impurity metal
ions into the host glass structure. Introduction of Yb
leads (Figs 3a and 3b) to the intensity increase of the
bands at 192, 227, 236, 365 cm–1 that correspond to the
presence of the As4S4 nanophase. The intensity of the
496 cm–1 band characteristic for the vibrations of S-S
bonds is decreased with the Yb introduction. The
difference spectra reveal changes occurred in the glass
structure upon variation of composition. From these
spectra, it can be seen that addition of Yb leads to the
intensity increase in the 1cm-150 band that
corresponds to vibrations of phase-decomposed S8 rings
and the 1cm-317 band, which can be attributed to
pyramidal structural AsS3 units with additional sulfur
atoms involved into (-S-S-) chains and joined pyramidal
fragments. Doping of As2S3 glasses with small amount
of Yb ions, up to 1 wt.%, only slightly affect the short-
range order structure of the host matrix. The main
observed effect after introduction of ytterbium into
As2S3 is the change of the relative concentration of the
main and non-stoichiometric structural units
characteristic for As2S3 glasses.
100 200 300 400 500
0.0
0.3
0.6
0.9
In
te
ns
ity
, a
rb
.u
n
it
Wavenumber, cm-1
1 - As
2
S
3
2 - As
2
S
3
:Cr 0.5 wt.%
1
2
19
2
2
2
7
2
3
6
3
1
7
346
3
65
498
Fig. 1. Raman spectra of As2S3 and As2S3:Cr 0.5 wt.%.
100 200 300 400 500
-0.09
-0.06
-0.03
0.00
0.03
0.06
In
te
n
si
ty
d
iff
e
re
n
ce
, a
rb
.u
n
it
Wavenumber, cm-1
As
2
S
3
:Cr 0.5 wt.%
192
227
317
365
498
431
Fig. 2. Differential Raman spectra of As2S3 doped with Cr
0.5 wt.% (relatively to As2S3).
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2014. V. 17, N 4. P. 341-345.
© 2014, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
343
100 200 300 400 500
0.0
0.2
0.4
0.6
0.8
1.0
In
te
n
si
ty
, a
rb
.u
n
it
Wavenumber, cm-1
1 - As
2
S
3
2 - As
2
S
3
:Yb 0.5 wt.%
3 - As
2
S
3
:Yb 1 wt.%
1
2
3
19
0
2
38
3
16
346
4
98
Fig. 3a. Raman spectra of As2S3, As2S3:Yb 0.5 wt.% and
As2S3:Yb 1 wt.%. Spectra are normalized by intensity of the
346 cm– 1 peak and shifted by equal distances in order of
appearance.
100 200 300 400 500
-0.015
0.000
0.015
In
te
n
si
ty
d
iff
er
en
ce
, a
rb
.u
ni
t
Wavenumber, cm-1
As
2
S
3
:Yb 0.5 wt.%
As
2
S
3
:Yb 1 wt.%
1
5
5
1
6
0
22
1
2
3
7
316
49
8
Fig. 3b. Difference Raman spectra of chalcogenide glasses:
As2S3:Yb 0.5 wt.% and As2S3+Yb 1 wt.% (relatively to As2S3).
Thermal properties
Thermogram for As-S:Cr with Cr content 0.75 wt.%
(heating rate 10 K/min) is shown in Fig. 4. It is
necessary to note that with increase of the heating rate,
Tg value is shifted towards higher temperatures.
Kissinger’s expression was used for estimating the
activation energy of glass transition. The obtained Tg
values for As2S3 with various concentrations of Cr and
Yb are presented in Table.
Table. Glass transition temperature Tg of doped As-S
glasses (q = 10 K/min).
Composition Tg, °С
As2S3 208.3
As2S3:Cr 0.5 wt.% 204.5
As2S3:Cr 0.75 wt.% 202.8
As2S3:Yb 0.5 wt.% 207
As2S3:Yb 1 wt.% 206.2
100 150 200 250
H
e
at
in
g
fl
o
w
E
X
O
Temperature, 0C
1 - As
2
S
3
2 - As
2
S
3
:Cr 0.5 wt.%
3 - As
2
S
3
:Cr 0.75 wt.%
T
g
1
2
3
Fig. 4a. Thermograms of As-S:Cr glass with Cr content 0, 0.5
and 0.75 wt.% at the heating rate 10 K/min.
100 150 200 250
Temperature, 0C
1 - As
2
S
3
:Yb 0.5 wt.%
2 - As
2
S
3
:Yb 1 wt.%
1
2
H
ea
tin
g
fl
ow
E
X
O
T
g
Fig. 4b. Thermograms of As2S3 with content of Yb 0.5 wt.%
and 1 wt.% at the heating rate 10 K/min.
Luminescence
Photoluminescence spectra for glasses As2S3:Cr with
different Cr composition are presented in Fig. 5. It can
be seen from the figure that the photoluminescence
intensity increases with the Cr concentration, thus,
showing the increased level of defects with the
chromium introduction having small effect on its shape.
Rare-earth luminescence As-S glasses modified by
Yb have two luminescence bands in the near IR range,
which are placed near 980 and 1060 nm (Fig. 6). In this
case, transitions from the excited state 2F5/2 to the main
state 2F7/2 that are characteristic for ion Yb3+ are
pronounced. The intensity of photoluminescence
increases with increase of the ytterbium concentration.
Magnetic properties
Pure chalcogenide glasses are diamagnetics. Introduction
of transitional and rare earth impurities changes magnetic
properties of the investigated chalcogenide glasses [13]. In
the fields near 5 T, the M(T) dependence was observed
(Fig. 7), which is characteristic for paramagnetics and
ferromagnetics in the paramagnetic temperature range
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2014. V. 17, N 4. P. 341-345.
© 2014, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
344
[13]. Measurements of magnetic properties (temperature
dependence of the specific magnetic moment) were
performed under various conditions of sample cooling. A
sample was cooled in zero external magnetic field, then
the magnetic field with specified magnitude was set. In
what follows, this magnetic field was maintained constant
during the sample heating. The interval of temperature
variation was chosen in such a way that the maximal
value of temperature exceeded the temperature of
transition into the paramagnetic state. Hereinafter, such
dependences are denoted as ZFC. Further, the sample was
cooled in the magnetic field and M = M(T) was obtained.
It is denoted as FC in figures.
800 1000 1200 1400
20
40
60
80
100
120
140
P
L
in
te
n
si
ty
, a
rb
. u
ni
t
Wavelength, nm
1 - As
2
S
3
2 - As
2
S
3
:Cr 0.5 wt.%
1
2
Fig. 5. Luminescence spectra of undoped As2S3 and doped
with Cr 0.5 wt.%.
900 950 1000 1050 1100 1150
0
1000
2000
3000
4000
P
L
in
te
ns
ity
, a
rb
. u
n
it.
Wavelength, nm
1 - As
2
S
3
:Yb 0.5 wt.%
2 - As
2
S
3
:Yb 1 wt.%
1
2
Fig. 6. Luminescence spectra of As2S3 doped with Yb: 0.5 and
1 wt.%.
0 100 200 300
-6.0x10-6
-5.0x10-6
-4.0x10-6
-3.0x10-6
M
(
A
m
2 /k
g
)
Temperature, K
FC As
2
S
3
:Cr 0.5 wt.%
ZFC As
2
S
3
:Cr 0.5 wt.%
FC As
2
S
3
:Cr 0.75 wt.%
ZFC As
2
S
3
:Cr 0.75 wt.%
Fig. 7. Temperature dependence of mass magnetization (M) in
As2S3 doped with Cr 0.5 and 1 wt.% (B = 5 T).
4. Discussion
Results on photoluminescence spectra for glasses
As2S3:Cr with different Cr content are in agreement with
the model proposed by Tanaka [10]. According to
Tanaka’s model, half-gap photoluminescence arises from
recombination of electrons, being trapped by anti-bonding
states of wrong (and strained) bonds at around the mid-
gap Fermi level, and holes in Urbach-edge states at the
valence-band top. The wrong bonds are considered as the
most dominant defects in covalent chalcogenide
semiconductors such as As2S(Se)3. The wrong-bond
density in As2S3 is markedly affected by the preparation
condition [11]. Also, it is necessary to note that the
density of the wrong bond in As2S(Se)3 is estimated at a
few atomic percent, which is consistent with the insensity
of photoluminescence on impurity concentrations up to
~0.1 at.%. At this level, the wrong bond concentration
change can be tracked by Raman spectroscopy as was
shown above. Raman measurements show that the
intensity of bands that correspond to the presence of As4S4
nanophase is increased with the growth of the Cr
concentration, that is, the number of the wrong As-As
bonds is increased. And due to increase of the number
(concentration) of the wrong As-As, the luminescence
intensity must be increased, which can be seen in Fig. 5.
Developments in photonics applications of
chalcogenide glasses have highlighted them as a matrix-
host for rare-earth ions [7-9]. Bishop et al. [12]
demonstrated the so-called broad-band excitation, i.e.,
excitation of rare-earth ions, not directly, but through
exciting the host chalcogenide glass having a broad
Urbach-edge spectrum. Chalcogenide glasses can be
doped by significant amounts of impurities (up to the
level of several atomic percents) without essential
changing the optical quality [14]. This feature can be
connected with the flexibility of the glass network, lesser
density of glass as compared to the crystal, presence of
nanovoids (which sizes can be estimated from positron
annihilation lifetime spectra using different formula
[15, 16]). It is necessary to note that introduction of rare
earth elements can change not only luminescent but also
magnetic properties of chalcogenide glasses.
5. Conclusions
Optical, thermal, luminescent and magnetic properties of
chalcogenide glasses can be changed by doping of
transitional and rare-earth metals. Photoluminescence of
As2S3 doped with Cr is well explained by the model
proposed by Tanaka [10]. Chalcogenide glasses can be
host for rare-earth metals, which provides a possibility to
simultaneously change both luminescent and magnetic
properties of glasses.
Acknowledgements
The research was supported by the project FP–7
SECURE–R21.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2014. V. 17, N 4. P. 341-345.
© 2014, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
345
References
1. I.D. Aggarwal, J.S. Sanghera, Development and
applications of chalcogenide glass optical fibers at
NRL // Journal of Optoelectronics and Advanced
Materials, 4(3), p. 665-678 (2002).
2. A.V. Stronski, M. Vlček, Photosensitive properties
of chalcogenide vitreous semiconductors in
diffractive and holographic technologies
applications // Journal of Optoelectronics and
Advanced Materials, 4(3), p. 699-704 (2002).
3. Amorphous Semiconductors, Topics in Applied
Physics, v.36, Eds. M.H. Brodsky, p. 176-185,
Springer-Verlag, Berlin, 1979.
4. N.F. Mott and E.A. Davis, Electron Processes in
Non-crystalline Materials. Clarendon press,
Oxford, p. 583, 1979.
5. A. Feltz, Amorphous Inorganic Materials and
Glasses. VCH, Weinheim, Germany, p. 446, 1993.
6. A.B. Seddon, Z. Tang, D. Furniss, S. Sujecki and
T.M. Benson, Progress in rare-earth-doped mid-
infrared fiber lasers // Opt. Exp. 18(25), p. 26704-
26719 (2010).
7. D. Lezal, Chalcogenide glasses – survey and
progress // Journal of Optoelectronics and
Advanced Materials, 5(1), p. 23-34 (2003).
8. S.O. Kasap, K. Koughia, M. Munzar, D. Tonchev,
D. Saitou, T. Aoki, Recent photoluminescence
research on chalcogenide glasses for photonics
applications // J. Non-Cryst. Solids, 353, p. 1364-
1371 (2007).
9. K. Tanaka, K. Shimakawa, Amorphous
Chalcogenide Semiconductors and Related
Materials. Springer, New York, 2011.
10. K. Tanaka, Photoluminescence in chalcogenide
glasses: revisited // Journal of Optoelectronics and
Advanced Materials, 15(11-12), p. 1165-1178
(2013).
11. K. Tanaka, The charged defect exists? // Journal of
Optoelectronics and Advanced Materials, 3(2),
p. 189-198 (2001).
12. G. Bishop, D.A. Turnbull, and B.G. Aitken,
Excitation of rare earth emission in chalcogenide
glasses by the broadband Urbach edge absorption //
J. Non-Cryst. Solids 266–269, p. 876-883 (2000).
13. A. Gubanova, Ts. Kryskov, A. Paiuk et al., Some
magnetic properties of chalcogenide glasses As2S3
and As2Se3 doped with Cr, Mn and Yb //
Moldavian J. Phys. Sci. 8(2), p. 178-185 (2009).
14. A.V. Stronski, M. Vlček, A.I. Stetsun, A. Sklenař,
P.E. Shepeliavyi, Raman spectra of Ag- and Cu-
photodoped As40S60-xSex films // J. Non-Cryst.
Solids, 270, p. 129-136 (2000).
15. A. Stronski, Positron annihilation lifetime
spectroscopy measurement of Ge5As37S58 glass //
Adv. Mater. Res. 854, p. 111-115 (2014).
16. O.I. Shpotyuk, M.M. Vakiv, M.V. Shpotyuk,
A. Ingram, J. Filipecki, A.P. Vaskiv, Free-volume
correlations in positron-sensitive annihilation
modes in chalcogenide vitreous semiconductors: on
the path from illusions towards realistic physical
description // Semiconductor Physics, Quantum &
Optoelectronics, 17(3), p. 243-251 (2014).
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2014. V. 17, N 4. P. 341-345.
PACS 07.20.Mc, 65.60+a, 75.30.Hx, 78.30.Ly, 78.55.Qr
Photoluminescence of As2S3 doped with Cr and Yb
A.V. Stronski1, O.P. Paiuk1, V.V. Strelchuk1, Iu.M. Nasieka1, M. Vlček2
1V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine,
41, prospect Nauky, 03028 Kyiv, Ukraine
2University of Pardubice, Faculty of Chemical Technology, Pardubice, Czech Republic
Abstract. The results of experimental researches of photoluminescence spectra in As2S3 glasses obtained by doping of Cr and Yb ions to As–S host matrix followed by Raman and calorimetric studies as well as low-temperature magnetization measurements have been given. Possible mechanisms of obtained effects are discussed.
Keywords: chalcogenide glass, photoluminescence, Raman spectra, thermal property, magnetization.
Manuscript received 07.02.14; revised version received 25.06.14; accepted for publication 29.10.14; published online 10.11.14.
1. Introduction
Chalcogenide glasses (ChGs) exhibit a number of interesting optical properties with various potential applications as reviewed in, for example [1, 2], etc. As frequently pointed out by various researchers, ChGs are promising materials for various applications because they are transparent over a wide range of wavelengths in the infrared region, they possess high refractive indices, low phonon energies and are easy to fabricate. Chalcogenide glasses can be used in applications in sensorics, infrared optics and optoelectronics. The glasses can be used for preparation of optical fibers both for passive and active applications.
The refractive index and its wavelength dependence, luminescent properties are among important parameters that determine the suitability of materials as optical media. The photoluminescence (PL) spectrum of arsenic chalcogenides when excited by light with ħω ≈ Eg (Eg is an optical bandgap energy) lies at about half the optical gap, which means that PL undergoes a strong Stokes shift, and it appears as a broad Gaussian-shaped spectrum with a peak energy EPL approximately at EPL ≈ Eg/2 [3-5]. Developments in photonics applications highlighted the chalcogenide glass as a host for rare-earth ions [1, 6-9].
Tanaka [10] proposed a new model for the half-gap PL. The latter arises from recombination of electrons, being trapped by anti-bonding states of wrong (and strained) bonds at around the mid-gap Fermi level, and holes in Urbach-edge states at the valence-band top. The wrong bond seems to be the most dominant defect in covalent chalcogenide semiconductors such as As2S(Se)3, irrespective of glass and crystal, and accordingly, this model can be applied to the corresponding crystals as well. The PL fatigue, which is more prominent in the glass, may arise from momentary trapped electrons (type I) and broken chemical bonds (type II) in disordered flexible lattices. However, complete understandings of the PL fatigue remain difficult as caused by some experimental limitations.
In this work, photoluminescence of As2S3 doped with Cr and Yb was investigated.
2. Experimental
The glasses of compositions As2S3, As2S3:Cr 0.5 wt.% and As2S3:Cr 0.75 wt.%, As2S3, As2S3:Yb 0.5 wt.%, As2S3:Yb 1 wt.% and As2S3:Yb 2 wt.% were prepared using the standard melt-quenching technique with constituent elements of 6N purity, which were melted in vacuum-sealed silica ampoules for 10…12 hours and subsequently quenched in air. Room temperature Raman spectra were recorded using a Fourier spectrophotometer Bruker IFS-55 Equinox with FRA-106 attachment.
Photoluminescence of As2S3 doped with Cr was studied within the 800…1600-nm region (T = 77 K, λex = 514 nm) using a HORIBA Jobin-Yvon T64000 spectrometer. Photoluminescence of As-S glasses modified with Yb was excited by a laser diode at the 980-nm wavelength with the radiation intensity 150 mW and was registered at room temperature using a Zolix SBP 300 monochromator (resolution ~1 nm) with Zolix CR131 attachment.
Thermal properties were studied using the DSC technique, Tg values for undoped and doped glasses were obtained. NETZSCH DSC 404 calorimeter (with accuracy ±0.5 K) was used in DSC measurements. Calorimetric measurements were carried out using powder samples (m ~ 20 mG) in argon atmosphere under temperature changes within 40…250 (С. The heating rate q = 10 K/min. Calibration of the calorimeter was carried out by melting pure metals In, Sn, Bi, Pb, Al, Cu with known values of temperature and enthalpy of melting.
Magnetization of the samples was measured with a Cryogenic S600 Super-conducting Quantum Interference Device (SQUID) magnetometer within the temperature range 5…400 K and in magnetic fields up to 5 T. A cryogenic system was completed with automated instrument control, data acquisition and analysis using the National Instrument’s LabVIEW software.
3. Results
Raman spectra
Introduction of Cr impurity (Fig. 1) leads to the intensity increase of the bands at 192, 227, 236,
1
cm
365
-
, which correspond to the presence of non-stoichiometric molecular fragments of the As4S4 nanophase. The intensity of the
1
cm
-
496
-
band, characteristic for the vibrations of S-S bonds, is decreased with the Cr introduction. The difference spectra (Fig. 2) reveal the changes occurred in the glass structure upon variation of composition. From these spectra, one can be see that addition of Cr leads to intensity increase of the
1
cm
-
150
-
band that corresponds to vibrations of phase-decomposed S8 rings and the
1
cm
-
317
-
band, which can be attributed to pyramidal structural AsS3 units with additional sulfur atoms involved into (-S-S-) chains and joined pyramidal fragments. The main observed effect under introduction of chromium into As2S3 is the change of the relative concentration of the main and non-stoichiometric structural units characteristic for As2S3 glasses.
Chalcogenide glasses As2S3 doped with ytterbium were investigated using Raman spectroscopy to obtain information regarding incorporation of impurity metal ions into the host glass structure. Introduction of Yb leads (Figs 3a and 3b) to the intensity increase of the bands at 192, 227, 236, 365 cm–1 that correspond to the presence of the As4S4 nanophase. The intensity of the 496 cm–1 band characteristic for the vibrations of S-S bonds is decreased with the Yb introduction. The difference spectra reveal changes occurred in the glass structure upon variation of composition. From these spectra, it can be seen that addition of Yb leads to the intensity increase in the
1
cm
-
150
-
band that corresponds to vibrations of phase-decomposed S8 rings and the
1
cm
-
317
-
band, which can be attributed to pyramidal structural AsS3 units with additional sulfur atoms involved into (-S-S-) chains and joined pyramidal fragments. Doping of As2S3 glasses with small amount of Yb ions, up to 1 wt.%, only slightly affect the short-range order structure of the host matrix. The main observed effect after introduction of ytterbium into As2S3 is the change of the relative concentration of the main and non-stoichiometric structural units characteristic for As2S3 glasses.
100
200
300
400
500
0.0
0.3
0.6
0.9
Intensity, arb.unit
Wavenumber, cm
-1
1 - As
2
S
3
2 - As
2
S
3
:Cr 0.5 wt.%
1
2
192
227
236
317
346
365
498
Fig. 1. Raman spectra of As2S3 and As2S3:Cr 0.5 wt.%.
100
200
300
400
500
-0.09
-0.06
-0.03
0.00
0.03
0.06
Intensity difference, arb.unit
Wavenumber, cm
-1
As
2
S
3
:Cr 0.5 wt.%
192
227
317
365
498
431
Fig. 2. Differential Raman spectra of As2S3 doped with Cr 0.5 wt.% (relatively to As2S3).
100
200
300
400
500
0.0
0.2
0.4
0.6
0.8
1.0
Intensity, arb.unit
Wavenumber, cm
-1
1 - As
2
S
3
2 - As
2
S
3
:Yb 0.5 wt.%
3 - As
2
S
3
:Yb 1 wt.%
1
2
3
190
238
316
346
498
Fig. 3a. Raman spectra of As2S3, As2S3:Yb 0.5 wt.% and As2S3:Yb 1 wt.%. Spectra are normalized by intensity of the 346 cm– 1 peak and shifted by equal distances in order of appearance.
100
200
300
400
500
-0.015
0.000
0.015
Intensity difference, arb.unit
Wavenumber, cm
-1
As
2
S
3
:Yb 0.5 wt.%
As
2
S
3
:Yb 1 wt.%
155
160
221
237
316
498
Fig. 3b. Difference Raman spectra of chalcogenide glasses: As2S3:Yb 0.5 wt.% and As2S3+Yb 1 wt.% (relatively to As2S3).
Thermal properties
Thermogram for As-S:Cr with Cr content 0.75 wt.% (heating rate 10 K/min) is shown in Fig. 4. It is necessary to note that with increase of the heating rate, Tg value is shifted towards higher temperatures. Kissinger’s expression was used for estimating the activation energy of glass transition. The obtained Tg values for As2S3 with various concentrations of Cr and Yb are presented in Table.
Table. Glass transition temperature Tg of doped As-S glasses (q = 10 K/min).
Composition
Tg, °С
As2S3
208.3
As2S3:Cr 0.5 wt.%
204.5
As2S3:Cr 0.75 wt.%
202.8
As2S3:Yb 0.5 wt.%
207
As2S3:Yb 1 wt.%
206.2
100
150
200
250
Heating flow EXO
Temperature,
0
C
1 - As
2
S
3
2 - As
2
S
3
:Cr 0.5 wt.%
3 - As
2
S
3
:Cr 0.75 wt.%
T
g
1
2
3
Fig. 4a. Thermograms of As-S:Cr glass with Cr content 0, 0.5 and 0.75 wt.% at the heating rate 10 K/min.
100
150
200
250
Temperature,
0
C
1 - As
2
S
3
:Yb 0.5 wt.%
2 - As
2
S
3
:Yb 1 wt.%
1
2
Heating flow EXO
T
g
Fig. 4b. Thermograms of As2S3 with content of Yb 0.5 wt.% and 1 wt.% at the heating rate 10 K/min.
Luminescence
Photoluminescence spectra for glasses As2S3:Cr with different Cr composition are presented in Fig. 5. It can be seen from the figure that the photoluminescence intensity increases with the Cr concentration, thus, showing the increased level of defects with the chromium introduction having small effect on its shape.
Rare-earth luminescence As-S glasses modified by Yb have two luminescence bands in the near IR range, which are placed near 980 and 1060 nm (Fig. 6). In this case, transitions from the excited state 2F5/2 to the main state 2F7/2 that are characteristic for ion Yb3+ are pronounced. The intensity of photoluminescence increases with increase of the ytterbium concentration.
Magnetic properties
Pure chalcogenide glasses are diamagnetics. Introduction of transitional and rare earth impurities changes magnetic properties of the investigated chalcogenide glasses [13]. In the fields near 5 T, the M(T) dependence was observed (Fig. 7), which is characteristic for paramagnetics and ferromagnetics in the paramagnetic temperature range [13]. Measurements of magnetic properties (temperature dependence of the specific magnetic moment) were performed under various conditions of sample cooling. A sample was cooled in zero external magnetic field, then the magnetic field with specified magnitude was set. In what follows, this magnetic field was maintained constant during the sample heating. The interval of temperature variation was chosen in such a way that the maximal value of temperature exceeded the temperature of transition into the paramagnetic state. Hereinafter, such dependences are denoted as ZFC. Further, the sample was cooled in the magnetic field and M = M(T) was obtained. It is denoted as FC in figures.
800
1000
1200
1400
20
40
60
80
100
120
140
PL intensity, arb. unit
Wavelength, nm
1 - As
2
S
3
2 - As
2
S
3
:Cr 0.5 wt.%
1
2
Fig. 5. Luminescence spectra of undoped As2S3 and doped with Cr 0.5 wt.%.
900
950
1000
1050
1100
1150
0
1000
2000
3000
4000
PL intensity, arb. unit.
Wavelength, nm
1 - As
2
S
3
:Yb 0.5 wt.%
2 - As
2
S
3
:Yb 1 wt.%
1
2
Fig. 6. Luminescence spectra of As2S3 doped with Yb: 0.5 and 1 wt.%.
0
100
200
300
-6.0x10
-6
-5.0x10
-6
-4.0x10
-6
-3.0x10
-6
M
(
Am
2
/kg
)
Temperature, K
FC As
2
S
3
:Cr 0.5 wt.%
ZFC As
2
S
3
:Cr 0.5 wt.%
FC As
2
S
3
:Cr 0.75 wt.%
ZFC As
2
S
3
:Cr 0.75 wt.%
Fig. 7. Temperature dependence of mass magnetization (M) in As2S3 doped with Cr 0.5 and 1 wt.% (B = 5 T).
4. Discussion
Results on photoluminescence spectra for glasses As2S3:Cr with different Cr content are in agreement with the model proposed by Tanaka [10]. According to Tanaka’s model, half-gap photoluminescence arises from recombination of electrons, being trapped by anti-bonding states of wrong (and strained) bonds at around the mid-gap Fermi level, and holes in Urbach-edge states at the valence-band top. The wrong bonds are considered as the most dominant defects in covalent chalcogenide semiconductors such as As2S(Se)3. The wrong-bond density in As2S3 is markedly affected by the preparation condition [11]. Also, it is necessary to note that the density of the wrong bond in As2S(Se)3 is estimated at a few atomic percent, which is consistent with the insensity of photoluminescence on impurity concentrations up to ~0.1 at.%. At this level, the wrong bond concentration change can be tracked by Raman spectroscopy as was shown above. Raman measurements show that the intensity of bands that correspond to the presence of As4S4 nanophase is increased with the growth of the Cr concentration, that is, the number of the wrong As-As bonds is increased. And due to increase of the number (concentration) of the wrong As-As, the luminescence intensity must be increased, which can be seen in Fig. 5.
Developments in photonics applications of chalcogenide glasses have highlighted them as a matrix-host for rare-earth ions [7-9]. Bishop et al. [12] demonstrated the so-called broad-band excitation, i.e., excitation of rare-earth ions, not directly, but through exciting the host chalcogenide glass having a broad Urbach-edge spectrum. Chalcogenide glasses can be doped by significant amounts of impurities (up to the level of several atomic percents) without essential changing the optical quality [14]. This feature can be connected with the flexibility of the glass network, lesser density of glass as compared to the crystal, presence of nanovoids (which sizes can be estimated from positron annihilation lifetime spectra using different formula [15, 16]). It is necessary to note that introduction of rare earth elements can change not only luminescent but also magnetic properties of chalcogenide glasses.
5. Conclusions
Optical, thermal, luminescent and magnetic properties of chalcogenide glasses can be changed by doping of transitional and rare-earth metals. Photoluminescence of As2S3 doped with Cr is well explained by the model proposed by Tanaka [10]. Chalcogenide glasses can be host for rare-earth metals, which provides a possibility to simultaneously change both luminescent and magnetic properties of glasses.
Acknowledgements
The research was supported by the project FP–7 SECURE–R21.
References
1.
I.D. Aggarwal, J.S. Sanghera, Development and applications of chalcogenide glass optical fibers at NRL // Journal of Optoelectronics and Advanced Materials, 4(3), p. 665-678 (2002).
2.
A.V. Stronski, M. Vlček, Photosensitive properties of chalcogenide vitreous semiconductors in diffractive and holographic technologies applications // Journal of Optoelectronics and Advanced Materials, 4(3), p. 699-704 (2002).
3.
Amorphous Semiconductors, Topics in Applied Physics, v.36, Eds. M.H. Brodsky, p. 176-185, Springer-Verlag, Berlin, 1979.
4.
N.F. Mott and E.A. Davis, Electron Processes in Non-crystalline Materials. Clarendon press, Oxford, p. 583, 1979.
5.
A. Feltz, Amorphous Inorganic Materials and Glasses. VCH, Weinheim, Germany, p. 446, 1993.
6.
A.B. Seddon, Z. Tang, D. Furniss, S. Sujecki and T.M. Benson, Progress in rare-earth-doped mid-infrared fiber lasers // Opt. Exp. 18(25), p. 26704-26719 (2010).
7.
D. Lezal, Chalcogenide glasses – survey and progress // Journal of Optoelectronics and Advanced Materials, 5(1), p. 23-34 (2003).
8.
S.O. Kasap, K. Koughia, M. Munzar, D. Tonchev, D. Saitou, T. Aoki, Recent photoluminescence research on chalcogenide glasses for photonics applications // J. Non-Cryst. Solids, 353, p. 1364-1371 (2007).
9.
K. Tanaka, K. Shimakawa, Amorphous Chalcogenide Semiconductors and Related Materials. Springer, New York, 2011.
10.
K. Tanaka, Photoluminescence in chalcogenide glasses: revisited // Journal of Optoelectronics and Advanced Materials, 15(11-12), p. 1165-1178 (2013).
11.
K. Tanaka, The charged defect exists? // Journal of Optoelectronics and Advanced Materials, 3(2), p. 189-198 (2001).
12.
G. Bishop, D.A. Turnbull, and B.G. Aitken, Excitation of rare earth emission in chalcogenide glasses by the broadband Urbach edge absorption // J. Non-Cryst. Solids 266–269, p. 876-883 (2000).
13.
A. Gubanova, Ts. Kryskov, A. Paiuk et al., Some magnetic properties of chalcogenide glasses As2S3 and As2Se3 doped with Cr, Mn and Yb // Moldavian J. Phys. Sci. 8(2), p. 178-185 (2009).
14.
A.V. Stronski, M. Vlček, A.I. Stetsun, A. Sklenař, P.E. Shepeliavyi, Raman spectra of Ag- and Cu-photodoped As40S60-xSex films // J. Non-Cryst. Solids, 270, p. 129-136 (2000).
15.
A. Stronski, Positron annihilation lifetime spectroscopy measurement of Ge5As37S58 glass // Adv. Mater. Res. 854, p. 111-115 (2014).
16.
O.I. Shpotyuk, M.M. Vakiv, M.V. Shpotyuk, A. Ingram, J. Filipecki, A.P. Vaskiv, Free-volume correlations in positron-sensitive annihilation modes in chalcogenide vitreous semiconductors: on the path from illusions towards realistic physical description // Semiconductor Physics, Quantum & Optoelectronics, 17(3), p. 243-251 (2014).
© 2014, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
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