The nature of red emission in porous silicon
The photoluminescence spectra of porous silicon at 77 and 300 K and their transformation during aging were investigated. The competition of two radiative recombination channels that have a common excitation mechanism was observed. It is shown that only one of them, which causes infrared emission ban...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2005
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| Назва видання: | Semiconductor Physics Quantum Electronics & Optoelectronics |
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| Цитувати: | The nature of red emission in porous silicon / L.Yu. Khomenkova, N.E. Korsunska, B.M. Bulakh, M.K. Sheinkman, T.R. Stara // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2005. — Т. 8, № 1. — С. 60-63. — Бібліогр.: 17 назв. — англ. |
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irk-123456789-1206402017-06-13T03:02:40Z The nature of red emission in porous silicon Khomenkova, L.Yu. Korsunska, N.E. Bulakh, B.M. Sheinkman, M.K. Stara, T.R. The photoluminescence spectra of porous silicon at 77 and 300 K and their transformation during aging were investigated. The competition of two radiative recombination channels that have a common excitation mechanism was observed. It is shown that only one of them, which causes infrared emission band and is present in as-prepared samples, is connected with excitonic recombination in Si nanocrystals. The second one that causes red emission band appears during aging is supposed to be connected with carrier recombination through oxide-related defects. It is shown that this channel dominates in aged samples. 2005 Article The nature of red emission in porous silicon / L.Yu. Khomenkova, N.E. Korsunska, B.M. Bulakh, M.K. Sheinkman, T.R. Stara // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2005. — Т. 8, № 1. — С. 60-63. — Бібліогр.: 17 назв. — англ. 1560-8034 PACS: 78.67.-n, 78.30-j, 78.55.-m. http://dspace.nbuv.gov.ua/handle/123456789/120640 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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The photoluminescence spectra of porous silicon at 77 and 300 K and their transformation during aging were investigated. The competition of two radiative recombination channels that have a common excitation mechanism was observed. It is shown that only one of them, which causes infrared emission band and is present in as-prepared samples, is connected with excitonic recombination in Si nanocrystals. The second one that causes red emission band appears during aging is supposed to be connected with carrier recombination through oxide-related defects. It is shown that this channel dominates in aged samples. |
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Article |
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Khomenkova, L.Yu. Korsunska, N.E. Bulakh, B.M. Sheinkman, M.K. Stara, T.R. |
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Khomenkova, L.Yu. Korsunska, N.E. Bulakh, B.M. Sheinkman, M.K. Stara, T.R. The nature of red emission in porous silicon Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Khomenkova, L.Yu. Korsunska, N.E. Bulakh, B.M. Sheinkman, M.K. Stara, T.R. |
| author_sort |
Khomenkova, L.Yu. |
| title |
The nature of red emission in porous silicon |
| title_short |
The nature of red emission in porous silicon |
| title_full |
The nature of red emission in porous silicon |
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The nature of red emission in porous silicon |
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The nature of red emission in porous silicon |
| title_sort |
nature of red emission in porous silicon |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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2005 |
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http://dspace.nbuv.gov.ua/handle/123456789/120640 |
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The nature of red emission in porous silicon / L.Yu. Khomenkova, N.E. Korsunska, B.M. Bulakh, M.K. Sheinkman, T.R. Stara // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2005. — Т. 8, № 1. — С. 60-63. — Бібліогр.: 17 назв. — англ. |
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Semiconductor Physics Quantum Electronics & Optoelectronics |
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Semiconductor Physics, Quantum Electronics & Optoelectronics, 2005. V. 8, N 1. P. 60-63.
PACS: 78.67.-n, 78.30-j, 78.55.-m.
The nature of red emission in porous silicon
L.Yu. Khomenkova, N.E. Korsunska, B.M. Bulakh, M.K. Sheinkman, T.R. Stara
V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine
41, prospect Nauky, 03028 Kyiv, Ukraine
Phone: +38 044 525 72 34; Fax: +38 044 525 83 42
E-mail: khomen@ukr.net
Abstract. The photoluminescence spectra of porous silicon at 77 and 300 K and their
transformation during aging were investigated. The competition of two radiative
recombination channels that have a common excitation mechanism was observed. It is
shown that only one of them, which causes infrared emission band and is present in as-
prepared samples, is connected with excitonic recombination in Si nanocrystals. The
second one that causes red emission band appears during aging is supposed to be
connected with carrier recombination through oxide-related defects. It is shown that this
channel dominates in aged samples.
Keywords: porous silicon, photoluminescence, recombination.
Manuscript received 01.12.04; accepted for publication 18.05.05.
1. Introduction
One of the most important theoretical and experimental
tasks in physics of silicon-based nano-structures is the
clarification of the nature of radiative transitions. One of
such systems is well-known porous silicon (PSi) that
shows bright red emission at room temperature. In spite
of numerous investigations, the nature of this emission is
currently under discussion [1 – 13]. One of the most
widespread models of red emission is excitonic
recombination in quantum confined silicon nanocrystals
[9]. However, a number of experimental results are hard-
to-explain within this model. For example, the red band
(R-band) demonstrates a different behavior in
dependence on preparation conditions and further
treatments. In particular, under cooling the peak position
of red photoluminescence (PL) shifts to the high-energy
side in different samples, to the low-energy one [8] or
doesn’t change [5]. Such a behavior of this band is
usually explained by the contribution of different
radiative channels to PL spectrum.
Beside, the excitonic recombination inside Si
nanocrystals, another radiative channels such as
electron-hole recombination through oxide-related
centers [5 – 7] or surface states [10] as well as
recombination of the excitons localized at Si=O bonds
[11] or in quantum confinement well at Si / SiO2
interface [8] were considered.
However, it is impossible to consider any of the
above-mentioned models to be proved completely, since
the PL components resulted from different
recombination channels were not observed
simultaneously as separated bands and their possible
contribution to wide emission spectrum observed in
porous Si was not extracted.
Different approaches can be used to discriminate the
radiative channels. One of them is the study of PL
spectra dependence on Si crystallite sizes when the latter
vary in a wide range. We used such an approach for
investigation of the emission properties of Si-SiO2 layers
prepared by magnetron sputtering [12, 13]. It was shown
that, at room temperature, the PL spectra of these layers
consist of several overlapping bands. The shift of peak
position with the change of Si nanocrystal sizes was
found only for the infrared PL band, while the peak
positions of another ones were constant. The latter bands
were attributed to silicon oxide defects. However, for
porous silicon, PSi, such an approach is low-effective
because PL spectra at room temperature are broad and
unstructured.
In this work, another approach based on the
investigation of the temperature behavior of PL spectra
and their transformation during PSi aging was used to
clarify the contribution of different radiative channels to
red emission.
2. Experimental procedures
The PSi layers were prepared by the electrochemical
etching of Si substrate (boron-doped, ρ = 10 Ohm⋅cm,
(100) orientation) in non-aqueous HF-ethanol electrolyte
(HF:C2H5OH = 2:1) at the current density
jA = 50 mA/cm2 and time duration tA = 10 min. PL and
PL excitation (PLE) spectra were measured at 77 and
300 K with the setup described in [5, 12, 14] under
excitation by a xenon lamp. To control Si nanocrystal
© 2005, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
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Semiconductor Physics, Quantum Electronics & Optoelectronics, 2005. V. 8, N 1. P. 60-63.
Fig. 1. PL spectra of PSi layer: as-prepared (1) and after aging
during 2 hours (2), 15 days (3) and 150 days (4) measured at
77 (a) and 300 K (b); c – the comparison of curves 3 from
Figs 1a and b.
sizes, the Raman scattering spectra were measured when
exciting by 487.9 nm line of the argon laser LGI-503
and detected with the setup based on a DFS-24
spectrometer with a cooled FEU-136 photomultiplier in
the photon-counting mode. To avoid the layer heating,
the power density of laser emission did not exceed
1.5 W/cm2. The Raman spectra measurements were
carried out at the room temperature.
3. Experimental results
The low-temperature PL spectra of PSi layers are shown
in Fig. 1a. The as-prepared samples demonstrate one
infrared emission band (IR-band) with a full-width at
half-maximum (FWHM) ∼ 0.14 eV (Fig. 1a, curve 1).
The aging in air for up to two weeks leads to the
decrease of PL intensity and shift of its peak to the high-
energy side (curves 2, 3). Simultaneously, the tightening
of high-energy PL edge to the high-energy side and then
the appearance of an additional PL band (R-band) is
observed. As follows from decomposition of curve 3
Fig. 2. Normalized PLE spectra of 15-days aged sample
measured at 300 K for 1.4 eV (squares) and 1.8 eV (circles).
The excitation energy is 3.5 eV.
Fig. 3. Raman scattering spectra of as-prepared (1) and 15-
days aged (2) samples. The curve 3 corresponds to the Raman
scattering from Si substrate.
from Fig. 1a (Fig. 1c), this R-band peaks at ~ 1.69 eV
and has the FWHM ~ 0.2 eV. After more prolong aging,
the PL intensity increases essentially, and again its
spectrum contains only one band, the maximum of
which shifts to the high-energy side up to 1.7 eV after
150 days aging (curves 4, 5). However, its FWHM
(0.35...0.4 eV) essentially exceeds the FWHM of the PL
band in the as-prepared sample.
At 300 K, the PL intensity in as-prepared samples is
very low, and the PL spectra contain one infrared band
(Fig. 1b, curve 1). Aging for 2 hours leads to the
increase of the PL intensity and to shift of the PL band
peak position from 1.55 to 1.7 eV. After more prolong
aging, the PL intensity increases, while the peak position
remains constant. PLE spectra of both bands coincide
(Fig. 2, curve 1) and show one broad band peaking at
3.5 eV.
© 2005, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
The Raman scattering spectra of as-prepared samples
show a broad band with the peak at 513 cm−1 (Fig. 3,
curve 1). After 15-days aging, the Raman band shifts to
61
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2005. V. 8, N 1. P. 60-63.
low-frequency side down to 508 cm−1. Besides, the
additional band at 519 cm−1 appears (curve 2).
Obviously, this band results from substrate (Fig. 3,
curve 3), and its appearance is due to the increase of
layer transparency during oxidation. The estimation of Si
nanocrystal sizes with using the calculation [15] shows
that, in as-prepared samples, the sizes of Si nanocrystals
are 4 nm while in the 15-days aged samples they are
only 3 nm.
4. Discussion
The above-mentioned results show that the high-energy
shift of the IR-band peak position correlates with the
decrease of Si nanocrystal sizes during aging. So, we can
ascribe IR-band to excitonic recombination inside Si
nanocrystals.
During aging, an additional R-band appears in the
low-temperature PL spectra, and its intensity increases
with the aging time (Fig. 1a, curves 2, 3). However, after
the prolong aging only one band is observed in the PL
spectra again. Because of its high FWHM, we can think
that this band is the superposition of IR- and R-ones. It is
confirmed by the shift of broad band peak position with
the aging time to 1.7 eV that coincides with the peak
position of R-band (Fig. 1a, curve 3). The last fact
means that R-band dominates in low-temperature PL
spectra after 150 days aging, and its peak position is
independent of aging time and crystallite sizes. As
Fig. 1b shows, the R-band dominates at 300 K after
2 hours aging. The coincidence of the PL peak positions
at 77 and 300 K after prolong aging means that the
R-band peak position is temperature independent. In
general case, this transformation of PL spectra during
aging and with temperature can be explained by the
change of IR- and R-bands contribution.
Since the R-band appears under natural oxidation and
its maximum position is independent of temperature, it is
possible to attribute this band to carrier recombination
through oxide-related centers. This is confirmed by the
observation of such a band in silicate glasses [10].
The intensity of IR-band decreases at the first stage
of aging. At the same time, the decomposition of curve 4
in Fig. 1a (not shown) indicates that its intensity
increases after prolong aging. As we have shown earlier
[14], the as-prepared samples are highly passivated,
while during aging the Pb-centers appear due to Si / SiO2
interface formation. So, we can attribute the decrease of
IR-band intensity at the beginning of aging to the
increase of the number of Pb-centers that are the centers
of non-radiative recombination. At the same time, the
increase of the IR-band intensity can be a result of the
barrier height increase, and the crystallite sizes decrease
due to the crystallite oxidation [17].
When IR- and R-band are observed separately (1 –
15 days aged samples), we can see that these bands have
the reverse temperature dependences: when heating the
IR-band intensity quenches while the R-band one
enhances (Fig. 1c). As the PLE spectra of these bands
are similar (Fig. 2), we can conclude that they have a
common excitation mechanism that is obviously the
light absorption in Si nanocrystals [7, 12, 16]. In this
case, the reverse temperature dependence of IR- and R-
band intensities can be caused by a competition of
recombination flows through Si nanocrystals and oxide-
related centers.
5. Conclusions
It is shown that the competition of two radiative
channels takes place in PSi samples. One of them that
causes the infrared band is due to the excitonic
recombination in Si nanocrystals. Another one can be
attributed to carrier recombination through oxide-related
defects and causes the red emission. It is shown that both
bands are excited due to light absorption by Si
nanocrystals, and the competition of radiative
recombination in Si nanocrystals as well as in oxide-
related defects takes place.
References
1. D.I. Kovalev, I.D. Yarostietzkii, T. Muschik, Fast
and slow visible luminescence bands of oxidized
porous Si // Appl. Phys. Lett. 64 (2), p. 214-216
(1994).
2. L. Tsybeskov, Yu.V. Vandyshev, P.M. Fauchet, Blue
emission in porous silicon: Oxygen-related
photoluminescence // Phys. Rev. B 49 (11), p. 7821-
7824 (1994).
3. H.D. Fuchs, M. Stutzmann, M.S. Brandt, M. Rosen-
bauer, J. Weber, A. Breischwerdt, P. Deak, M. Car-
dona, Porous silicon and siloxene: Vibrational and
structural properties // Ibid. 48 (11), p. 8172-8189
(1993).
4. G.G. Qin, Y.Q. Jia, Mechanism of visible lumine-
scence in porous silicon // Solid State Communs 86
(9), p. 559-563 (1993).
5. S.M. Prokes, Light emission in thermally oxidized
porous silicon: Evidence for oxide-related lumine-
scence // Appl. Phys. Lett. 62 (25), p. 3244-3246
(1993).
6. T.V. Torchynska, M. Morales Rodriguez, F.G. Ba-
carril-Espinoza, N.E. Korsunskaya, L.Yu. Khomen-
kova, L.V. Scherbina, Ballistic effect in red photo-
luminescence of Si wires // Phys. Rev. B 65, p.
115313-1 – 115313-7 (2002).
7. N. Korsunska, M. Baran, L. Khomenkova, V. Yuk-
hymchuk, Y. Goldstein, E. Savir, J. Jedrzejewski,
Mechanism of photoexcitation of oxide-related
emission bands in Si-SiO2 systems // Mater. Sci. and
Eng. C 23, p. 691-696 (2003).
8. Y. Kanemitsu, S. Okamoto, Resonantly excited
photoluminescence from porous silicon: Effects of
© 2005, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
62
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2005. V. 8, N 1. P. 60-63.
surface oxidation on resonant luminescence spectra //
Phys. Rev. B 56 (4), p. R1696 – R1699 (1997).
9. G. Cullis, L.T. Canham, P.D.J. Calcott, The
structural and luminescence properties of porous
silicon // J. Appl. Phys. 82 (3), p. 909-965 (1997).
10. F. Koch, V. Petrova-Koch, T. Muschik, The
luminescence of porous Si: the case for the surface
state mechanism // J. Lumin. 57, p. 271-282 (1993).
11. Murayama, S. Miyazaki, M. Hirose, Excitation and
recombination processes in porous silicon // Solid
State Communs 93, p. 841-846 (1995).
12. N. Korsunska, L. Khomenkova, V. Yukhimchuk,
B. Jumayev, T. Torchynska, A. Many, E. Savir,
Y. Goldstein, J. Jedrzejewski, Defect-related
luminescence of Si / SiO2 layers // J. Phys.: Condens.
Mater. 14, p. 13217-13221 (2002).
13. T.V. Torchynska, F.G. Bacarril-Espinoza, Y. Gold-
stein, E. Savir, J. Jedrzejewskii, L.Yu. Khomenkova,
N. Korsunska, V. Yukhimchuk, Nature of visible
luminescence of co-sputtered Si-SiOx systems //
Physica B 340-342, p. 1119-1123 (2003).
14. Korsunska, M. Baran, B. Bulakh, L. Khomenkova,
V. Yukhimchuk, V. Papusha, Influence of Si / SiOx
interface formation on luminescence characteristics
of Si-SiO2 // Izv. RAN, Ser. Fiz. 67 (2), p. 223-227
(2003).
15. I.H. Campbell, P.M. Fauchet, The effect of
microcrystal size and shape on one phonon raman
spectra of crystalline semiconductors // Solid State
Communs 58 (10), p. 739-741 (1986).
16. N. Korsunska, L. Khomenkova, V. Yukhimchuk,
B. Jumayev, T. Torchynska, A. Many, E. Savir,
Y. Goldstein, J. Jedrzejewski, Nature of visible
luminescence and its excitation in Si-SiOx systems //
J. Lumin. 102-103, p. 705-711 (2003).
17. Yu.V. Kryuchenko, and A.V. Sachenko, Quantum
efficiency of exciton luminescence in low-
dimensional structures with the indirect energy gap //
Physika E 14, p. 299-312 (2002).
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