Thermofield Cr→Cr²⁺ recharging resulting in anomalous intensification of Cr²⁺ emission in ZnS:Cr thin-film electroluminescent structures
For the first time, an anomalous strong increase of the Cr²⁺ emission intensity (I) with increasing the applied voltage (V) has been discovered in ZnS:Cr thin-film electroluminescent structures (TFELS) instead of the I(V) dependence saturation typical of TFELS of the MISIM type, where M is an...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2007
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| Цитувати: | Thermofield Cr→Cr²⁺ recharging resulting in anomalous intensification of Cr²⁺ emission in ZnS:Cr thin-film electroluminescent structures / N.A. Vlasenko, P.F. Oleksenko, Z.L. Denisova, M.A. Mukhlyo, L.I. Veligura // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2007. — Т. 10, № 3. — С. 87-90. — Бібліогр.: 13 назв. — англ. |
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irk-123456789-1181312017-06-06T16:59:34Z Thermofield Cr→Cr²⁺ recharging resulting in anomalous intensification of Cr²⁺ emission in ZnS:Cr thin-film electroluminescent structures Vlasenko, N.A. Oleksenko, P.F. Denisova, Z.L. Mukhlyo, M.A. Veligura, L.I. For the first time, an anomalous strong increase of the Cr²⁺ emission intensity (I) with increasing the applied voltage (V) has been discovered in ZnS:Cr thin-film electroluminescent structures (TFELS) instead of the I(V) dependence saturation typical of TFELS of the MISIM type, where M is an electrode, I is an insulator layer and S is an EL film. The dependence of I on the transferred charge (Q) is very superlinear, whereas the luminance of the emission of hot electrons, which takes place simultaneously with the Cr²⁺ emission, increases proportionally to Q as it happens usually in TFELS. The increase of I and Q is accompanied by rising the sample temperature up to 30 – 50 °C. However, the emission spectrum that is inherent to the ⁵E → ⁵T₂ transition in the 3d shell of a Cr²⁺ ion is not changed in this case. The above effects are explained by Cr⁺ → Cr²⁺ thermofield recharging, which results in an increase of the number not only of free electrons, but also of Cr²⁺ radiation centers. The most probable mechanism of such a recharging is the Frenkel-Pool field-stimulated thermal ionization of Cr⁺ ions, whose ionization energy is 0.65…0.82 eV. 2007 Article Thermofield Cr→Cr²⁺ recharging resulting in anomalous intensification of Cr²⁺ emission in ZnS:Cr thin-film electroluminescent structures / N.A. Vlasenko, P.F. Oleksenko, Z.L. Denisova, M.A. Mukhlyo, L.I. Veligura // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2007. — Т. 10, № 3. — С. 87-90. — Бібліогр.: 13 назв. — англ. 1560-8034 PACS 78.60.Fi, 73.50.Fq, 71.55.Gs, 68.55.L http://dspace.nbuv.gov.ua/handle/123456789/118131 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| description |
For the first time, an anomalous strong increase of the Cr²⁺ emission intensity
(I) with increasing the applied voltage (V) has been discovered in ZnS:Cr thin-film
electroluminescent structures (TFELS) instead of the I(V) dependence saturation typical
of TFELS of the MISIM type, where M is an electrode, I is an insulator layer and S is an
EL film. The dependence of I on the transferred charge (Q) is very superlinear, whereas
the luminance of the emission of hot electrons, which takes place simultaneously with the
Cr²⁺ emission, increases proportionally to Q as it happens usually in TFELS. The
increase of I and Q is accompanied by rising the sample temperature up to 30 – 50 °C.
However, the emission spectrum that is inherent to the ⁵E → ⁵T₂ transition in the 3d shell
of a Cr²⁺ ion is not changed in this case. The above effects are explained by Cr⁺ → Cr²⁺
thermofield recharging, which results in an increase of the number not only of free
electrons, but also of Cr²⁺ radiation centers. The most probable mechanism of such a
recharging is the Frenkel-Pool field-stimulated thermal ionization of Cr⁺
ions, whose ionization energy is 0.65…0.82 eV. |
| format |
Article |
| author |
Vlasenko, N.A. Oleksenko, P.F. Denisova, Z.L. Mukhlyo, M.A. Veligura, L.I. |
| spellingShingle |
Vlasenko, N.A. Oleksenko, P.F. Denisova, Z.L. Mukhlyo, M.A. Veligura, L.I. Thermofield Cr→Cr²⁺ recharging resulting in anomalous intensification of Cr²⁺ emission in ZnS:Cr thin-film electroluminescent structures Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Vlasenko, N.A. Oleksenko, P.F. Denisova, Z.L. Mukhlyo, M.A. Veligura, L.I. |
| author_sort |
Vlasenko, N.A. |
| title |
Thermofield Cr→Cr²⁺ recharging resulting in anomalous intensification of Cr²⁺ emission in ZnS:Cr thin-film electroluminescent structures |
| title_short |
Thermofield Cr→Cr²⁺ recharging resulting in anomalous intensification of Cr²⁺ emission in ZnS:Cr thin-film electroluminescent structures |
| title_full |
Thermofield Cr→Cr²⁺ recharging resulting in anomalous intensification of Cr²⁺ emission in ZnS:Cr thin-film electroluminescent structures |
| title_fullStr |
Thermofield Cr→Cr²⁺ recharging resulting in anomalous intensification of Cr²⁺ emission in ZnS:Cr thin-film electroluminescent structures |
| title_full_unstemmed |
Thermofield Cr→Cr²⁺ recharging resulting in anomalous intensification of Cr²⁺ emission in ZnS:Cr thin-film electroluminescent structures |
| title_sort |
thermofield cr→cr²⁺ recharging resulting in anomalous intensification of cr²⁺ emission in zns:cr thin-film electroluminescent structures |
| publisher |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| publishDate |
2007 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/118131 |
| citation_txt |
Thermofield Cr→Cr²⁺ recharging resulting in anomalous intensification of Cr²⁺ emission in ZnS:Cr thin-film electroluminescent structures / N.A. Vlasenko, P.F. Oleksenko, Z.L. Denisova, M.A. Mukhlyo, L.I. Veligura // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2007. — Т. 10, № 3. — С. 87-90. — Бібліогр.: 13 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
| work_keys_str_mv |
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Semiconductor Physics, Quantum Electronics & Optoelectronics, 2007. V. 10, N 3. P. 87-90.
© 2007, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
87
PACS 78.60.Fi, 73.50.Fq, 71.55.Gs, 68.55.L
Thermofield Cr+→Cr2+ recharging resulting in anomalous
intensification of Cr2+ emission in ZnS:Cr thin-film
electroluminescent structures
N.A. Vlasenko, P.F. Oleksenko, Z.L. Denisova, M.A. Mukhlyo, L.I. Veligura
V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine
41, prospect Nauky, Kyiv 03028, Ukraine
Abstract. For the first time, an anomalous strong increase of the Cr2+ emission intensity
(I) with increasing the applied voltage (V) has been discovered in ZnS:Cr thin-film
electroluminescent structures (TFELS) instead of the I(V) dependence saturation typical
of TFELS of the MISIM type, where M is an electrode, I is an insulator layer and S is an
EL film. The dependence of I on the transferred charge (Q) is very superlinear, whereas
the luminance of the emission of hot electrons, which takes place simultaneously with the
Cr2+ emission, increases proportionally to Q as it happens usually in TFELS. The
increase of I and Q is accompanied by rising the sample temperature up to 30 – 50 °C.
However, the emission spectrum that is inherent to the 5E → 5T2 transition in the 3d shell
of a Cr2+ ion is not changed in this case. The above effects are explained by Cr+ → Cr2+
thermofield recharging, which results in an increase of the number not only of free
electrons, but also of Cr2+ radiation centers. The most probable mechanism of such a
recharging is the Frenkel-Pool field-stimulated thermal ionization of Cr+ ions, whose
ionization energy is 0.65…0.82 eV.
Keywords: electroluminescence, thin films, ZnS:Cr, thermofield ionization, Cr+→ Cr2+
recharging.
Manuscript received 08.05.07; accepted for publication 27.09.07; published online 30.11.07.
1. Introduction
An intensive emission in the near-infrared region from
1.7 to 2.8 µm takes place in ZnS(Se):Cr thin-film
electroluminescent structures (TFELS) [1-3]. The same
emission is observed in photoluminescence of
ZnS(Se):Cr crystals [4]. This emission is due to the
5E → 5T2 transition in the 3d shell of Cr2+ ions. In the
spectrum of ZnS(Se):Cr TFELS, there is also a week
emission in the region of 0.4−1.0 µm that results from
intraband indirect transitions of hot electrons [1, 3, 5]. It
is known that some number of Cr+ ions is side-by-side
with Cr2+ ions in ZnS(Se):Cr. The photo-stimulated
appearance of Cr+ ions in ZnS(Se):Cr crystals has been
revealed by investigating the electronic paramagnetic
resonance (EPR) at low temperatures This has been
explained by Cr2+ → Cr+ photorecharging [6-10]. It has
been reported in [7] that Cr+ ions are present in ZnS:Cr
crystals even without any illumination. The existence of
these ions in ZnS:Cr TFELS has been confirmed by
studying the magnetic field effect on the emission of hot
electrons at 4.2 K [5]. It has been shown that a decrease
of the intensity of this emission in the magnetic field
results from the exchange scattering of electrons on Cr+
ions. In addition, a band connected with Cr+ ions has
been found in the photodepolarization spectrum of
ZnS:Cr TFELS (see below). The reverse Cr+ → Cr2+
recharging, which leads to a decrease of the Cr+ EPR
signal, has been revealed when ZnS(Se):Cr crystals were
heated [8-10] or illuminated by infrared light
simultaneously with the photo-stimulation [6, 8-10]. The
maximum of the photoquenching was observed at
photon energies of 0.7 [6, 8], 0.9 [9], and 1.1 eV [8, 10].
The thermal and optical ionization energies of Cr+ ions
equal to 0.65 - 0.82 eV and 0.7 – 1.1 eV, respectively,
have been determined from these data. In this paper, it is
reported on the discovery of an effect that evidences, on
author's opinion, the existence of the thermofield Cr+ →
Cr2+ recharging in ZnS:Cr TFELS under certain
excitation conditions.
2. Experimental procedures
Samples under study consist of MISIM structures
deposited on a glass substrate, where M are ITO and Al
electrodes, I are insulator layers (SiO2/Al2O3, ~270 nm),
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2007. V. 10, N 3. P. 87-90.
© 2007, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
88
165 170 175 180 185 190
0.5
1.0
1.5
2.0
2.5
165 170 175 180 185 190
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
V , V
lg L , cd/m
2
2
1
1'
1
2
lg I , arb.un.
a)
lg Q , µ K/сm 2
V , V
b)
Fig. 1. (a) Voltage dependence of Cr2+ emission intensity
(1, 2) and luminance of hot electrons emission (1′). (b)
Voltage dependence of transferred charge f = 20 kHz.
Measurement was without sample cooling (1, 1′) and with
cooling it by air flow (2).
and S is a ZnS:Cr El film (~650 nm). To increase the
transparency of the lower electrode in the near-infrared
region, the thin ITO films (60–80 nm) with rather high
resistance (−300 Ohm/□) were used. The I layers and ZnS
film were deposited by electron-beam evaporation. The
latter was doped during the deposition by simultaneous
thermal evaporation of Cr. The Cr concentration was
>1020 cm−3. Annealing in vacuum was performed after the
ZnS:Cr film deposition at 550°C for 1 h.
Electroluminescence was excited by a sinusoidal
voltage of 10–20 kHz. The emission in the region from
1.5 to 3 µm was recorded by a PbS photodetector set up
beyond an MDR-12 monochromator. In the visible
region, a FPI luminance meter was used. The charge (Q)
transferred through the EL film for the applied voltage
cycle was measured with a Sawyer-Tower circuit
commonly used for TFELS [11]. The sample
temperature (7) was measured by a thermocouple. The
flow of cold air was used to cool the sample.
3. Results and discussion
For the first time, the following effect has been revealed
in the voltage dependence of the intensity (I) of the Cr2+
emission at high frequencies ( f > 10 kHz). A very strong
increase of I takes place at high voltages (Fig. la, curve 1)
when a saturation in the I(V) dependence of TFELS is
usually observed [11]. Some larger increment of the
transferred charge also arises simultaneously, but it is
much less than that of I (Fig. 1b, curve 1). The luminance
(L) of the emission of hot electrons has the tendency to
saturation with voltage increasing at first (Fig. 1a,
curve 1′). However, the L(V) dependence becomes steeper
after that. It should be noted that the intensification of the
emission of hot electrons in this case is significantly
weaker than that of the Cr2+ emission.
The comparison of the dependences of I and L on
the transferred charge (Fig. 2, curve 1 and 1´) shows that
both values increase with Q identically up to the voltage,
at which the steeper increase of I, L, and Q begins. The
essentially different character of the I(Q) and L(Q)
dependences takes place at higher voltages. The former
becomes more superlinear with the exponent (n) equal to
4 – 6, whereas the dependence of L on Q is nearly linear,
which should be expected. It is known that the
luminance of TFELS is proportional to Q at high V when
the field in an EL film almost does not increase due to
the redistribution of the applied voltage between I and S
layers due to an increase of the active current passing
through the latter.
It was supposed that the above-mentioned increase
of Q is connected with some rising of the sample
temperature. The rather high capacitive and active
currents in the TFELS under study at f = 10–20 kHz
(0.1–0.3 A/cm) cause a significant voltage drop (10–
20 V) on the high-resistance ITO electrode and
consequently its heating. As a result, the whole sample
can be also heated. Indeed, the measurement of the
sample temperature shows that the effect described
above is accompanied by the rising of T from room
temperature (~20 °C) up to 30 – 50 °C. The cooling of
the sample by a cold air flow results in a significant
decrease of the effect (Fig. 1, 2, curve 2).
lg , K/ см
-0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0
0.0
0.5
1.0
1.5
2.0
2.5
Q µ
2
lg I , arb.un.
1'
1
2
Fig. 2. Dependence of Cr2+ emission intensity and luminance
of hot electrons emission on transferred charge. f = 20 kHz.
Numeration of curves is the same as in Fig. 1.
µC
µC/cm2
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2007. V. 10, N 3. P. 87-90.
© 2007, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
89
t, s
0 20 40 60 80 100 120
0.0
0.5
1.0
-0.30
-0.15
0.00
-0.2 -0.1
0.5
1.0
lgQ, µ K/cm
2
lg I , arb.un.
1
2
lg I , arb.un. lgQ, µ K/cm
Fig. 4. Dependence of Cr2+ emission intensity (1) and
transferred charge (2) on time after applying of fixed rather
high voltage. V = 187 V; f = 20 kHz. In insertion: dependence
of Cr2+ emission intensity on transferred charge in this case.
Normalized PDP current
1 2 3 4
Photon energy, eV
1.0
0.8
0.6
0.4
0.2
0.0
2
1
Fig. 5. Normalized PDP spectrum of ZnS:Cr TFELS with Cr
concentration of 0.4 wt.% (1) and 1.4 wt.% (2). Charging of
sample was by DC voltage of 70 V with +Al polarity. Spec-
trum was not corrected for equal number of testing photons.
, mcm
1.5 2.0 2.5 3.0
0
40
80
120
λ
I , arb.un.
1
2
x5
Fig. 3. Emission spectrum of ZnS:Cr TFELS in near-infrared
region at 175 V (1) and 187 V (2). f = 20 kHz. Spectrum was
not corrected for spectral sensitivity of PbS detector.
It should be emphasized that the EL spectrum in
the region from 1.7 to 3 µm, in which there is the
emission band of Cr2+ ions, is the same before and after
the appearance of the above effect (Fig. 3).
The increase of I, Q, and T takes also place in time
after applying a sufficiently high fixed voltage (Fig. 4).
The larger increase is observed for the first minute. It
becomes less after this and stops. The increase of the
Cr2+ emission intensity in this case is much more than
the increase of Q. The quantity I increases in time as Qn
where n ≈ 6 (see insertion in Fig. 4) in accordance with
the I(Q) dependence at increasing voltage (Fig. 2).
From the experimental results described above, we
can draw the following conclusion concerning the
mechanism of the observed effect. The heating of the
ZnS:Cr film up to 30 – 50 °C in the presence of a high
electric field, which is ≥ 2 MV/cm when the effect takes
place, results in the thermofield ionization of some
rather deep centers with an ionization energy (Ei) of 0.5–
0.9 eV. Consequently, the number of free electrons, i.e.,
Q, increases. This only assumption (without one more
suggestion about the nature of deep centers) is sufficient
to explain the linear increase of the luminance of the
emission of hot electrons with increasing Q. However,
the very superlinear I(Q) dependence can be explained
by assuming also that the thermofield ionization causes
an increase of the number not only of free electrons, but
also the radiation centers, i.e., Cr2+ ions. This means that
the thermofield Cr+ → Cr2+ recharging takes place. This
conclusion is also confirmed by the following. First, the
effect enhances with increasing the Cr concentration in
the ZnS:Cr film. Secondly, a superlinear increase of the
EL intensity when Q increases and T rises up to ~50 °C
was not observed in any from a great number of studied
TFELS with such activators as Mn, Tb, Er, and Ce [11].
The presence of Cr+ ions in the ZnS:Cr films is
confirmed, as was noted above, by the dependence of the
intensity of the emission of hot electrons on the
magnetic field [5]. This is also borne out by the
photodepolarization (PDP) spectra of the ZnS:Cr
TFELS. The typical PDP spectrum is given in Fig. 5. It
is seen that there is an impurity photocurrent in the
region of 0.7 – 2 eV, which increases relative to the
main maximum at ~3.5 eV with increasing the Cr
concentration. The main maximum is due, as was
supposed previously [2], to the ionization of the
[ ] 0 2
ZnCr + isovalent trap that arises when Cr2+ ions
substitute for Zn2+ ions in ZnS. The near-infrared region
µm
µC/cm2
lgQ, µC/cm2
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2007. V. 10, N 3. P. 87-90.
© 2007, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
90
of the impurity photocurrent coincides with the spectral
region, in which the photoquenching of the Cr+ EPR
signal was observed [6, 8–10], i.e., Cr+ → Cr2+ photo-
recharging takes place. In addition, the energy of the
long-wavelength edge of this region in the PDP
spectrum (0.7–0.75 eV) coincides well with the thermal
ionization energy of Cr+ ions that was determined from
the thermal quenching of the Cr+ EPR signal (0.65 –
0.82 eV) [6, 8-10]. The nature of other peaks observed in
the PDP spectrum of the ZnS:Cr TFELS will be a
subject of another paper.
The possible mechanism of the thermofield
ionization of centers with Ei = 0.65–0.82 eV in the field
(F) of ≥2 MV/cm and the temperature up to 50 °C can be
the Frenkel-Pool field-stimulated thermal ionization [12]
or multiphonon assisted tunneling [13]. According to the
former, the ionization energy of a center with Coulomb
potential well is lower in a high field than in a low field
by
πε
eFeE =∆ , where e is the electron charge and ε is
the dielectric constant. At F = 2 MV/cm, ∆E ≈ 0.4 eV.
Thus, the Cr+ ionization energy in such a field can be
0.3–0.35 eV according to the Frenkel-Pool mechanism.
The probability of thermal ionization of centers with
such potential barrier at T = 30–50 °C is rather high,
whereas the multiphonon assisted processes have usually
a low possibility. The decisive conclusion concerning
the mechanism of the discovered thermofield Cr+ → Cr2+
recharging needs an additional study.
4. Conclusions
For the first time, the unusually strong intensification of
the Cr2+ emission has been discovered in the ZnS:Cr
TFELS with an increase of the voltage at F ≥ 2 MV/cm.
This emission intensifies very superlinearly with the
transferred charge that also increases due to some
heating of the sample. The increasing Q at such a field
when T rises up to ≤330 K evidences that the thermo-
field ionization of some rather deep centers takes place.
This explains the observed linear with Q increase of the
luminance of the emission of hot electrons without one
more additional assumption about the nature of these
centers. The anomalous superlinear dependence of the
Cr2+ emission intensity on Q can be only explained with
the additional assumption that the ionized centers are
Cr2+ ions. These ions are present alongside with Cr2+
ions in the ZnS:Cr films and have a thermal ionization
energy of 0.65 - 0.82 eV. The thermofield Cr+ → Cr2+
recharging results in the increase of the number of both
free electrons and radiative centers. The exponent equal
to 5–6 in the I(Q) dependence can be explained taking
into account that each of the electrons passing through
the EL film is capable of the impact excitation of several
Cr2+ ions. Two mechanisms of thermofield Cr+ → Cr2+
recharging are possible: namely, the Frenkel-Pool field-
stimulated thermal ionization and the multiphonon
assisted tunneling. The estimation of a decrease of Ei of
Cr+ ions in the field that there is in the ZnS:Cr film
allows us to conclude preliminarily that the former has
advantage over the latter. The decisive conclusion
concerning the mechanism of thermofield Cr+ → Cr2+
recharging discovered in the ZnS:Cr TFELS needs an
additional study.
References
1. A.V. Vasilyev, N.A. Vlasenko, Z.L. Denisova,
Ya.F. Kononets, A.I. Riskin, A.Ya. Chomyak //
Optoelektronika i Poluprovodnikovaya Tekhnika
25, p. 68 (1993) (in Russian).
2. N.A. Vlasenko, Z.L. Denisova, Ya.F. Kononets,
L.I. Veligura, Yu.A. Tsyrkunov // J. SID 12, p. 1
(2004).
3. L.I. Veligura, N.A. Vlasenko, Z.L. Denisova,
V.Yu. Goroneskul, Ya.F. Kononets, Yu.A. Tsyr-
kunov // Optoelektronika i Poluprovodnikovaya
Tekhnika 39, p. 124 (2004) (in Russian).
4. S.B. Mirov, V.V. Fedorov, K. Graham, I.S.
Moskalev // Opt. Lett. 27, No 11, p. 909 (2002).
5. N.A. Vlasenko, A.E. Belyaev, Z.L. Denisova,
Ya.F. Kononets, A.V. Komarov, L.I. Veligura //
Semiconductor Physics, Quantum Electronics and
Optoelectronics 8, No 1, p. 25 (2005).
6. H.D. Fair, R.D. Ewing, F.E. Williams // Phys. Rev.
144, p. 298 (1966).
7. M. Goddewski, M. Kaminska // J. Phys. C 13, p.
6537 (1980).
8. T. Taki, H. Bő // J. Phys. Soc. Jpn 25, No 5, p.
1324 (1968).
9. F.F. Kodzespirov, M.F. Bulanij, I.A. Tereb // Fiz.
Tverd. Tela 16, p. 3159 (1974) (in Russian).
10. V.N. Martinov, I.A. Gorn // Kristallografiya 32, p.
131 (1987) (in Russian).
11. Y.O. Ono, Electroluminescent Displays. World
Scientific, Singapore, p. 33-36 (1995).
12. Ya.I. Frenkel // J. Eksp. Teor. Fiz. 8, p. 1893
(1938) (in Russian).
13. F.I. Dalidchik // J. Eksp. Teor. Fiz. 74, p. 472
(1978) (in Russian).
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