Effect of acetone vapor treatment on photoluminescence of porous nc-Si–SiOx nanostructures
The effect of treatment in saturated acetone vapors on the spectral composition and intensity of photoluminescence (PL) in porous oblique deposited SiOx films is studied. As a result of this treatment followed by high-temperature annealing at the temperature 930 °C, considerable PL intensity grow...
Gespeichert in:
| Veröffentlicht in: | Semiconductor Physics Quantum Electronics & Optoelectronics |
|---|---|
| Datum: | 2009 |
| Hauptverfasser: | , , , |
| Format: | Artikel |
| Sprache: | English |
| Veröffentlicht: |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2009
|
| Online Zugang: | https://nasplib.isofts.kiev.ua/handle/123456789/118680 |
| Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Zitieren: | Effect of acetone vapor treatment on photoluminescence of porous nc-Si–SiOx nanostructures / I.Z. Indutnyi, K.V. Michailovska, V.I. Min’ko, P.E. Shepeliavyi // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2009. — Т. 12, № 2. — С. 105-109. — Бібліогр.: 15 назв. — англ. |
Institution
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
nasplib_isofts_kiev_ua-123456789-118680 |
|---|---|
| record_format |
dspace |
| spelling |
Indutnyi, I.Z. Michailovska, K.V. Min’ko, V.I. Shepeliavyi, P.E. 2017-05-30T19:33:48Z 2017-05-30T19:33:48Z 2009 Effect of acetone vapor treatment on photoluminescence of porous nc-Si–SiOx nanostructures / I.Z. Indutnyi, K.V. Michailovska, V.I. Min’ko, P.E. Shepeliavyi // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2009. — Т. 12, № 2. — С. 105-109. — Бібліогр.: 15 назв. — англ. 1560-8034 PACS 78.55.Mb, 79.60.Jv, 81.40.Ef https://nasplib.isofts.kiev.ua/handle/123456789/118680 The effect of treatment in saturated acetone vapors on the spectral composition and intensity of photoluminescence (PL) in porous oblique deposited SiOx films is studied. As a result of this treatment followed by high-temperature annealing at the temperature 930 °C, considerable PL intensity growth and the small blueshift of PL peak position are observed in the porous, column-like structure films containing Si nanocrystals. A more intense shortwave band (peak position – 540-560 nm) appears in the PL spectrum of these structures, in addition to the longwave band (760-780 nm). Both PL bands in treated samples are characterized by monomolecular radiative recombination, which can be attributed to annihilation of excitons in silicon nanocrystals embedded into oxide matrix (longwave band) and in carbon-enriched matrix near surface of oxide nanocolumns (shortwave band). The possibility to control the PL characteristics of the porous structures in a wide spectral range by above treatment is shown. en Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України Semiconductor Physics Quantum Electronics & Optoelectronics Effect of acetone vapor treatment on photoluminescence of porous nc-Si–SiOx nanostructures Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
Effect of acetone vapor treatment on photoluminescence of porous nc-Si–SiOx nanostructures |
| spellingShingle |
Effect of acetone vapor treatment on photoluminescence of porous nc-Si–SiOx nanostructures Indutnyi, I.Z. Michailovska, K.V. Min’ko, V.I. Shepeliavyi, P.E. |
| title_short |
Effect of acetone vapor treatment on photoluminescence of porous nc-Si–SiOx nanostructures |
| title_full |
Effect of acetone vapor treatment on photoluminescence of porous nc-Si–SiOx nanostructures |
| title_fullStr |
Effect of acetone vapor treatment on photoluminescence of porous nc-Si–SiOx nanostructures |
| title_full_unstemmed |
Effect of acetone vapor treatment on photoluminescence of porous nc-Si–SiOx nanostructures |
| title_sort |
effect of acetone vapor treatment on photoluminescence of porous nc-si–siox nanostructures |
| author |
Indutnyi, I.Z. Michailovska, K.V. Min’ko, V.I. Shepeliavyi, P.E. |
| author_facet |
Indutnyi, I.Z. Michailovska, K.V. Min’ko, V.I. Shepeliavyi, P.E. |
| publishDate |
2009 |
| language |
English |
| container_title |
Semiconductor Physics Quantum Electronics & Optoelectronics |
| publisher |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| format |
Article |
| description |
The effect of treatment in saturated acetone vapors on the spectral composition
and intensity of photoluminescence (PL) in porous oblique deposited SiOx films is
studied. As a result of this treatment followed by high-temperature annealing at the
temperature 930 °C, considerable PL intensity growth and the small blueshift of PL peak
position are observed in the porous, column-like structure films containing Si
nanocrystals. A more intense shortwave band (peak position – 540-560 nm) appears in
the PL spectrum of these structures, in addition to the longwave band (760-780 nm).
Both PL bands in treated samples are characterized by monomolecular radiative
recombination, which can be attributed to annihilation of excitons in silicon nanocrystals
embedded into oxide matrix (longwave band) and in carbon-enriched matrix near surface
of oxide nanocolumns (shortwave band). The possibility to control the PL characteristics
of the porous structures in a wide spectral range by above treatment is shown.
|
| issn |
1560-8034 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/118680 |
| citation_txt |
Effect of acetone vapor treatment on photoluminescence of porous nc-Si–SiOx nanostructures / I.Z. Indutnyi, K.V. Michailovska, V.I. Min’ko, P.E. Shepeliavyi // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2009. — Т. 12, № 2. — С. 105-109. — Бібліогр.: 15 назв. — англ. |
| work_keys_str_mv |
AT indutnyiiz effectofacetonevaportreatmentonphotoluminescenceofporousncsisioxnanostructures AT michailovskakv effectofacetonevaportreatmentonphotoluminescenceofporousncsisioxnanostructures AT minkovi effectofacetonevaportreatmentonphotoluminescenceofporousncsisioxnanostructures AT shepeliavyipe effectofacetonevaportreatmentonphotoluminescenceofporousncsisioxnanostructures |
| first_indexed |
2025-11-26T16:30:21Z |
| last_indexed |
2025-11-26T16:30:21Z |
| _version_ |
1850628144487202816 |
| fulltext |
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 2. P. 105-109.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
105
PACS 78.55.Mb, 79.60.Jv, 81.40.Ef
Effect of acetone vapor treatment on photoluminescence
of porous nc-Si–SiOx nanostructures
I.Z. Indutnyi, K.V. Michailovska, V.I. Min’ko, P.E. Shepeliavyi
V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine
41, prospect Nauky, 03028 Kyiv, Ukraine
E-mail: indutnyy@isp.kiev.ua
Abstract. The effect of treatment in saturated acetone vapors on the spectral composition
and intensity of photoluminescence (PL) in porous oblique deposited SiOx films is
studied. As a result of this treatment followed by high-temperature annealing at the
temperature 930 °C, considerable PL intensity growth and the small blueshift of PL peak
position are observed in the porous, column-like structure films containing Si
nanocrystals. A more intense shortwave band (peak position – 540-560 nm) appears in
the PL spectrum of these structures, in addition to the longwave band (760-780 nm).
Both PL bands in treated samples are characterized by monomolecular radiative
recombination, which can be attributed to annihilation of excitons in silicon nanocrystals
embedded into oxide matrix (longwave band) and in carbon-enriched matrix near surface
of oxide nanocolumns (shortwave band). The possibility to control the PL characteristics
of the porous structures in a wide spectral range by above treatment is shown.
Keywords: nanocrystals, silicon oxide, photoluminescence, thin film.
Manuscript received 13.01.09; accepted for publication 18.03.09; published online 20.03.09.
1. Introduction
Recently, fabrication of Si-based light emitting materials
has been a very active area of research stimulated by its
potential application in Si-based optoelectronic devices.
Since the discovery of visible photoluminescence (PL) in
porous silicon [1], efficient room-temperature PL has
been realized in several nanometer-sized Si materials [2-
6]. Recent investigations were focused on Si-rich
dielectric thin films (mainly SiOx) made by techniques
compatible with the microelectronic industry. To fabricate
these films, a few basic techniques are usually used:
plasma-enhanced deposition, ion implantation, laser
ablation, magnetron sputtering, evaporation in vacuum,
etc. All these methods allow to fabricate films with
required x, and then the SiOx layers are annealed at high
temperature. As a result, Si nanoclusters 1-5 nm in size
are formed in the oxide matrix. The structure of the
nanoparticles depends on the annealing temperature:
annealing at temperatures below 900 °C results in
formation of amorphous inclusions, whereas at higher
temperatures, the Si nanocrystals are formed, with the
electronic structure modified by the quantum-confinement
effect [2, 4-6]. With decreasing dimensions of the
nanoclusters, the peak of the emission spectrum shifts to
shorter wavelengths.
In the previous study [7], we suggested method of
controlling the dimensions of Si nanoparticles in the
oxide matrix, namely, the use of oblique deposition of Si
monoxide thermally evaporated in vacuum. During such
deposition, SiOx films with a porous (column-like)
structure are formed. The thermally stimulated formation
of Si nanoinclusions in such films occurs in a restricted
volume of the SiOx columns with a small diameter.
These results in the formation of small-sized silicon
nanoclusters (nc-Si) compared to the clusters formed in
continuous films of the same composition. In this case,
we observe a broadening and a shift of the PL band to
longer wavelengths in the spectrum.
One of the most important factors influencing the
characteristics of PL is the state of the Si–SiOx interface.
The Si–SiOx interface can be modified by adsorption of
the compounds of necessary composition. The adsorption
is most efficient in porous structures at enhanced pressure
and temperature. In this paper, we report the results of
studying the effect of treatment in acetone vapors (carbon-
containing compounds) on PL of the porous nc-Si–SiOx
structures produced by oblique deposition.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 2. P. 105-109.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
106
Fig. 1. SEM micrographs of SiOx film cross-section:
(a) for the samples deposited at β = 75°, and (b) for that
deposited at β = 60°.
2. Experiment
The samples were produced by thermal evaporation of
Cerac Inc. silicon monoxide (with 99.9 % purity) in
vacuum (the residual pressure was (1–2)×10–3 Pa).
As substrates, we used two-sided polished Si
wafers. During deposition, the substrates were oriented
at the angles β = 0°, 60° and 75° between the normal to
the substrate surface and the direction to the evaporator.
The thickness of the films were monitored in situ
by the quartz-crystal-oscillator monitor system (КIТ-1)
and measured after deposition by a microinterferometer
(МII-4). The thickness of normally deposited films was
equal to 250-350 nm, for oblique deposited films – 400-
700 nm.
Some of the SiOx samples (except for the reference
ones) were kept for two hours in the pressure-tight
autoclave that contained the certain amount of acetone
(CH3COCH3) at the temperature 200 °С, here the
pressure of acetone vapors in autoclave was 18 atm.
Then all the samples were annealed in vacuum at the
temperature 930 °C for 15 min to produce nanocrystal-
line silicon inclusions in the oxide matrix [3]. Some of
the reference samples were treated in acetone vapors
after annealing.
The PL spectra were recorded at room temperature
using a system based on a ZMR-3 monochromator. The
PL signal was excited by radiation of an N2 laser at the
wavelength 337 nm and violet light-emitting diode
EDEV-1LA1 (wavelength 400 nm) which was used for
measurements of PL intensity dependence on the
excitation power. The signal was detected using a
FEU-51 photomultiplier, and PL spectra were
normalized to the spectral sensitivity of the experimental
system. SEM apparatus (ZEISS EVO 50XVP) was used
to observe the cross-section of annealed samples.
Selective etching of nc-Si–SiOx samples was conducted
in a weak solution of hydrofluoric acid.
3. Results and discussion
In Fig. 1, cross-sectional views of SiOx films oblique
deposited on silicon wafer are shown, where Fig. 1a
shows SEM micrograph of the sample deposited at
β = 75°, and Fig. 1b – sample deposited at β = 60°. As
can be seen in this figure, the investigated SiOx films
have a porous (inclined column-like) structure with the
column diameters of 10-100 nm. An angle of column
inclination, their dimensions and volume of pores in the
structure of films depend on the deposition angle. The
porosity of these samples (volume share of pores) were
measured in the previous paper [8], and it was equal to
34 and 53 % for the samples deposited at β = 60° and
75°, accordingly. High-temperature annealing of oblique
deposited SiOx films do not change porosity and
column-like structure of the samples.
The composition of the films (the parameter x) was
determined using compositional dependence of the
position of the basic IR band peak in spectra of SiOx
layers within the range 1000-1100 cm–1, as established in
[9]. This band corresponds to the transverse stretching
vibrations of the bridge-coordinated oxygen atoms (Si–
O–Si stretching mode). Since only the vibrations in the
silicon-oxygen phase are active in this spectral range,
while the Si–Si bond vibrations cannot be recorded, this
method can be used to determine the composition of the
oxide matrix in both as-prepared and annealed samples
containing the silicon phase. The stoichiometric
parameter x determined by this method is 1.42 and 1.51
for the samples deposited at the angles 60° and 75°,
respectively [7]. The difference in chemical composition
is related to the porosity of the films, as described
previously [7, 8]. During annealing, the SiOx oxide is
layered into Si and SiO2, and the stoichiometric
parameter of the oxide matrix (determined from the IR
spectra) is x ≈ 1.9 for all the samples.
Fig. 2 shows the PL spectra of two annealed porous
samples deposited at the angle 60°, namely, the
reference sample (curve a) and the sample treated in
acetone vapors in the autoclave before annealing
(curve b). It can be seen that for the untreated (reference)
sample two broad PL bands are observed. One, more
intensive with a maximum at ~780 nm and second,
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 2. P. 105-109.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
107
400 500 600 700 800 900
50
100
150
200
250 b
aPL
in
te
ns
ity
, a
rb
.u
ni
ts
λ, nm
Fig. 2. PL spectra of annealed SiOx samples deposited at
the angle 60°: the reference sample (a) and that treated in
acetone vapors in autoclave before annealing (b). Both
samples were annealed in vacuum at 930 °C for 15 min.
400 500 600 700 800 900
0
20
40
60
c
b
a
PL
in
te
ns
ity
, a
rb
. u
ni
ts
λ, nm
Fig. 3. PL spectra of annealed SiOx samples deposited at
the angle 75°: the reference sample (a), the sample treated
in acetone vapors in autoclave before annealing (b), and
the sample after etching in 0.1 % solution of HF during
20 s (c). The samples were annealed in vacuum at 930 °C
for 15 min.
considerably less intensive, is in a visible range of
spectrum (maximum at ~560 nm). The intense longwave
band that appears in the PL spectrum is connected with
the quantum-confinement effect of nc-Si, which
appeared in the matrix of oxide during the high
temperature annealing of SiOx films [10, 11]. The
shortwave band is determined, to our opinion, by
radiative recombination of excited charges on the
surface defects of oxide nanocolumns. In PL spectra of
continuous non-porous nc-Si–SiOx structures deposited
at β = 0°, this band in the PL spectrum is absent, which
confirms our supposition.
After treatment in the autoclave before annealing
(curve b) two bands in PL spectrum are also observed.
But the intensity of both bands increase, more
considerably for the shortwave one. The peak of the
shortwave band is shifted to shorter wavelengths slightly
– to 550 nm. This band is more intense than the
longwave one, and longwave band becomes more wide
and asymmetric, with a peak in the range of 750-770 nm.
PL spectra of obliquely deposited at the angle 75°
samples non-treated (curve a), treated in autoclave (b)
and both annealed at 930 °C are shown in Fig. 3. It can
be seen that for the untreated (reference) sample a broad
PL band is observed with a peak at ~760 nm, which can
be connected also with the quantum-confinement effect
and exciton annihilation in nc-Si that appear during
annealing of SiOx film (curve a). The shortwave band is
not observed by contrast to the spectrum in Fig. 2
(curve a). The samples deposited at the angle 75° have
higher porosity than deposited at β = 60°. It can result in
a higher concentration of non-radiative recombination
centers on the surface of oxide nanocolumns. The non-
radiative recombination quenches the radiative
recombination of excited charge carriers near the surface
of oxide nanocolumns that explains absence of the
shortwave band.
Treatment in the autoclave before high-temperature
annealing causes noticeable changes in PL spectra of
these samples. The PL intensity grows significantly, too.
In the visible range of spectrum, an intensive band
appears with a maximum near 540 nm. The unstructured
PL spectrum, which can be interpreted as superposition
of a few bands corresponding to various sizes of nc-Si, is
observed in IR region.
Analysis of PL spectra of obliquely deposited at the
angles 75° and 60° samples shows that treatment in the
autoclave before annealing at high temperatures causes
similar changes of the spectra. These changes are
characterized by growth of the PL intensity, appearance
of an intense band in the visible range of spectrum and a
small blue shift of the bands.
Some of the samples were treated in the autoclave
by using acetone vapors after high-temperature
annealing. This treatment does not induce any noticeable
changes in the intensity, shape, or position of the bands
in the PL spectrum.
Using a light-emitting diode EDEV-1LA1
(400 nm) for PL excitation, we explored the dependence
of PL intensity on the intensity of excitation. Fig. 4
shows the dependence of PL intensity taken at the peak
(760 nm) of infrared emission (curve b) and at the peak
of shortwave (540 nm) band (curve a) for the sample
obliquely deposited at the angle 75° and treated in the
autoclave. It can be seen that the PL intensity for both
bands grows linearly with increasing in the intensity of
excitation.
The linear dependence between intensities of
luminescence and excitation has been obtained
theoretically in the work [12], where the mechanism of
exciton recombination in nanocrystals was investigated.
It indicates that both PL bands of the treated samples can
be related with the quantum-confinement effect and
exciton annihilation in nc-Si.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 2. P. 105-109.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
108
0,5 1,0 1,5 2,0 2,5
10
20
30
40
50
60
70
P
L
in
te
ns
ity
, a
rb
.u
ni
ts
Excitation intensity, mW/cm2
a
b
Fig. 4. Dependence of the PL intensity on the excitation
intensity for SiOx film obliquely deposited at the angle 75° and
treated in the autoclave. PL intensity at the peak (760 nm) of
the infrared emission (b) and at the peak of shortwave
(540 nm) band (a).
400 500 600 700 800 900
10
20
30
40
50
60
c
b
a
PL
in
te
ns
ity
, a
rb
. u
ni
ts
λ, nm
Fig. 5. PL spectra of the sample obliquely deposited at the
angle 60° and treated in the autoclave before (a), and after
etching in 1 % solution of HF during 20 s (b) and 40 s (с).
The second confirmation of this assumption is the
dependence of PL maxima of both bands on the content
of silicon in deposited SiOx films. The sample deposited
at the angle 60° contains much silicon than deposited at
the angle 75° (x = 1.42 and 1.51 [7]). During the high
temperature annealing, in the first film larger nc-Si are
formed, and PL maximum shifts to longer wavelengths
(780 and 760 nm for the samples, deposited at 60° and
75°, accordingly). The spectral position of shortwave PL
bands that appear in the treated films also correlate with
the content of silicon in initial layers (560 and 540 nm,
accordingly).
With the purpose to more definitively determine
the origin of shortwave bands, we investigated the
influence of the selective etching on the PL spectra of
the autoclave-treated nc-Si–SiOx samples. The etching of
the samples was performed in weak (0.1-1 %) water
solutions of HF at room temperature. As known, HF
solution dissolves SiO2, while the rate of SiC and Si
dissolution in HF solutions is very small [13].
Fig. 5 shows PL spectra of the sample obliquely
deposited at the angle 60° and treated in the autoclave
before etching (curve a), and after etching in 1 %
solution of HF for 20 and 40 s (curves b and с,
accordingly). It can be seen that etching of the sample
results in gradual lowering the PL intensity in all the
spectral range, more actively in its shortwave region.
The maximum of the longwave PL band gradually shifts
to shorter wavelengths, the shortwave PL band shifts and
disappears. After etching for 40 s in the PL spectrum,
one wide band is presented with its peak at 680 nm.
The similar result has been obtained for the
samples obliquely deposited at the angle 75°, treated and
annealed in the same conditions. In the PL spectrum of
these samples after etching in 0.1 % solution of HF, one
wide band is present with the peak at 670-675 nm
(Fig. 3, curve с). The intensity of this PL band is
considerably less than before etching (Fig. 3, curve b).
The shortwave shift of PL bands and decrease in
their intensity as a result of etching is possible to be
explained by dissolution of SiO2 layer on surface of
oxide nanocolumns and following oxidation of silicon
atoms on nc-Si surface. It results in the decreasing nc-Si
size, and the PL band is shifted to the shortwave side.
Fast diminishing and disappearance of the shortwave PL
band shows that this band is related with the radiative
centers or nc-Si, which located near the surface of oxide
nanocolumns and can be removed under dissolution of
the surface SiO2 layer.
Appearance of the intense shortwave band after
barometric treatment in acetone vapors can be caused by
an effect of carbon impurities. It was shown [14] that, at
high temperatures (750-900 °C), acetone reacts with the
silicon surface, which results in formation of the SiCx
layer. Introduction of a considerable amount of carbon
into the oxide matrix containing Si nanocrystals provides
a means for noticeable shifting the PL spectrum to
shorter wavelengths [15]. Therefore, our results may be
interpreted similarly to that done in [15]: during
annealing, the adsorbed acetone reacts with the silicon
nanocrystals (in the small-sized oxide columns and near
the surface of the columns) to form SiCx surrounding of
these nanocrystals, which results in the shift of the PL
spectrum to shorter wavelengths. Since the modification
of nanocrystals with adsorbed molecules in the course of
annealing occurs at the surface of the columns, the nc-
Si–matrix interface is modified first for those
nanocrystals that are formed in columns smaller in
diameter or located near the surface of the columns.
Nanocrystals formed in the bulk of larger columns
remain surrounded by the oxide. Therefore, the PL
spectrum exhibits two bands: one, at longer
wavelengths, corresponds to nanocrystals in the oxide
matrix, and the other, at shorter wavelengths, to nc-Si in
Si-C surrounding.
Another possible mechanism of appearance of the
shortwave PL band is thermostimulated formation of the
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 2. P. 105-109.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
109
local radiative centers on the surface of oxide
nanocolumns. During annealing, carbon can form the
Si=C, Si–C or O–Si–C bonds. These bonds provide
effective luminescent centers and passivate the interface
between Si core and surrounding oxide. Except for it, the
substantial increase the PL intensity after barometric
treatment of investigated samples is well explained by
passivation of broken silicon bonds on the nc-Si surface.
4. Conclusions
In this study, SEM measurements show that obliquely
deposited at the angle 75° and 60° SiOx films have
porous column-like structure, porosity of which depends
on the angle of deposition. The effect of barometric
processing these films in acetone vapors before high-
temperature (930 °C) annealing on the light-emission
characteristics of nc-Si–SiOx structures is examined. It is
ascertained that, as a result of this treatment, the increase
in the PL intensity, the small blueshift of PL peak
position are observed, and a more intense shortwave
band (peak position – 540-560 nm) appears in the PL
spectrum of these structures, in addition to longwave
band (760-780 nm). For both bands the position of
maxima depends on the composition of initial layers
(content of silicon in SiOx film), which depends on the
angle of deposition.
Both PL bands in treated samples are characterized
by monomolecular radiative recombination, which can
be attributed to annihilation of excitons in silicon
nanocrystals embedded into oxide matrix (longwave
band), and in nc-Si in carbon-enriched matrix near the
surface of oxide nanocolumns (shortwave band). The
effect of selective etching on the PL spectra of the
autoclave-treated nc-Si–SiOx samples has confirmed the
assumption that the intense shortwave band appearing
after treatment is related with the radiative centers or
nanocrystals located near the surface of oxide
nanocolumns.
Thus, the barometric treatment of porous oxide
layers in acetone vapors at elevated temperatures is an
efficient method that provides means to increase the PL
intensity of nc-Si–SiOx structures and to vary the
spectral composition of emission over a wide spectral
region.
References
1. L.T. Canham, Silicon quantum wire array
fabrication by electrochemical and chemical
dissolution of wafers // Appl. Phys. Lett. 57,
p. 1046-1048 (1990).
2. M. Molinary, H. Rinnert and H. Vergnat, Visible
photoluminescence in amorphous SiOx thin films
prepared by silicon evaporation under a molecular
oxygen atmosphere // Appl. Phys. Lett. 82, p. 3877-
3879 (2003).
3. V.Ya. Bratus’, V.A. Yukhimchuk, L.I. Berezhinsky
et al., Structural transformations and silicon
nanocrystallite formation in SiOx films //
Semiconductors 35(7), p. 821-826 (2001).
4. D. Nesheva, C. Raptis, A. Perakis et al., Raman
scattering and photoluminescence from Si
nanoparticles in annealed SiOx thin films // J. Appl.
Phys. 92, p. 4678-4683 (2002).
5. 4. I.P. Lisovskyy, I.Z. Indutnyy, B.N. Gnennyy
et al., Structural and phase changes in SiOx films
under thermal vacuum treatments// Fizika i
Tekhnika Poluprovodnikov 37, p. 98-103 (2003) (in
Russian) [Semiconductors 37, p. 97 (2003)].
6. B.G. Fernandez, M. Lopez, C. Garcia et al.,
Influence of average size and interface passivation
on the spectral emission of Si nanocrystals embed-
ded in SiOx // J. Appl. Phys. 89, p. 237-243 (2001).
7. I.Z. Indutnyy, I.Yu. Maidanchuk, V.I. Min’ko,
Visible photoluminescence from annealed porous
SiOx films // J. Optoelectron. and Adv. Mater. 7,
p. 1231-1236 (2005).
8. V.A. Dan’ko, I.Z. Indutnyy, I.Y. Maidanchuk et al.,
Formation of the photoluminescence structure
based on SiOx porous films // Optoelectronika i
poluprovodnikovaya tekhnika 39, p. 65-72 (2004)
(in Ukrainian).
9. M. Nakamura, Y. Mochizuki, K. Usami et al.,
Infrared absorption spectra and compositions of
evaporated silicon oxide (SiOx) // Solid State
Communs 50, p. 1079-1081 (1984).
10. S.V. Svechnikov, E.B. Kaganovich, Luminescent
properties of Si nanostructures (review) //
Optoelectronika i poluprovodnikovaya tekhnika 39,
p. 5-26 (2004) (in Ukrainian).
11. I.Z. Indutnyy, I.Yu. Maidanchuk, V.I. Min’ko
et al., Effect of chemical treatment on photo-
luminescence spectra of SiOx layers containing Si
nanoparticles // Fizika i Tekhnika Poluprovodnikov
41 (10), p. 1265-1271 (2007) (in Russian).
12. P.K. Kashkarov, B.V. Kamenev, E.A. Konstanti-
nova et al., Dynamics of noneqilibrium charge
carriers in silicon quantum wires // Uspekhi
fizicheskikh nauk 168 (5), p. 577-582 (1998).
13. G. Wilieke, K. Kellermann // Semicond. Sci.
Technol. 11, p. 415-420 (1996).
14. T. Takami, S. Ishidzuka, Y. Igari, H. Range,
I. Kusunoki, Reaction of Si(111) surface with
acetone // Thin Solid Films 376, p. 89-98 (2000).
15. S.Y. Seo, K.S. Cho, J.H. Shin, Intense blue-white
luminescence from carbon-doped silicon-rich
silicon oxide // Appl. Phys. Lett. 84, p. 717-719
(2004).
|