Preparation and characterization of ZrO2:Sm amorphous thin films by solid state photochemical deposition method

Article abstract of DOI:10.1016/j.jpcs.2010.06.002

Thin films of ZrO₂ loaded with 10, 30 and 50 mol% Sm were prepared by a photochemical method using thin films of metal acetylacetonate complexes as precursors. The photolysis of these films induces the fragmentation of the acetylacetonate ligand and the partial reduction of metal ion together with volatile organic compounds. When the metallic complex is exposed to air, the product of the reaction is metal oxide. The photoreactivity of these films was monitored by FT-IR spectroscopy, followed by a post-annealing treatment process. The obtained films were characterized by X-ray photoelectron spectroscopy and atomic force microscopy. Photoluminescense studies of the films employed 400 nm radiation for excitation of the Sm ions present. The emission spectra showed signals arising from the ⁴G_5/2→ ⁶H_J (J=3/2, 7/2, 9/2) transitions, where the ⁴G_5/2→⁶H_3/2 transition has the highest intensity. The concentration dependence of the PL intensity was also studied. A maximum PL intensity was observed with 10 mol% Sm content but then diminished with higher Sm concentrations.

Full text of DOI:10.1016/j.jpcs.2010.06.002

Journal of Physics and Chemistry of Solids 71 (2010) 1367–1372
Contents lists available at ScienceDirect
Journal of Physics and Chemistry of Solids
journal homepage: www.elsevier.com/locate/jpcs
Preparation and characterization of ZrO :Sm amorphous thin films by solid
2
state photochemical deposition method
a,n
a
a
b
c
c
d
G. Cabello , L. Lillo , C. Caro , B. Chornik , M.A. Soto , R. del R ı´ o , M. Tejos
a
Departamento de Ciencias B a´ sicas, Facultad de Ciencias, Universidad del B ´ı o-B ´ı o, Campus Fernando May, Chill a´ n, Chile
b
Departamento de F ´ı sica, Facultad de Ciencias F ´ı sicas y Matem a´ ticas, Universidad de Chile, Casilla 487-3, Santiago 8370415, Chile
c
Depto Qu ´ı mica-F ´ı sica y Depto de Qu ´ı mica Inorg a´ nica, Facultad de Qu ´ı mica, Pontificia Universidad Cat o´ lica de Chile, Casilla 306, Santiago 609441, Chile
Facultad de Ciencias, Universidad de Valpara ´ı so, Av. Gran Breta n˜ a 1111 Playa Ancha Valpara ´ı so, Chile
d
a r t i c l e i n f o
a b s t r a c t
Article history:
Thin films of ZrO2 loaded with 10, 30 and 50 mol% Sm were prepared by a photochemical method using
thin films of metal acetylacetonate complexes as precursors. The photolysis of these films induces the
fragmentation of the acetylacetonate ligand and the partial reduction of metal ion together with volatile
organic compounds. When the metallic complex is exposed to air, the product of the reaction is metal
oxide. The photoreactivity of these films was monitored by FT-IR spectroscopy, followed by a post-
annealing treatment process. The obtained films were characterized by X-ray photoelectron spectro-
scopy and atomic force microscopy.
Received 10 August 2009
Received in revised form
3
1 May 2010
Accepted 8 June 2010
Keywords:
A. Amorphous materials
A. Thin films
Photoluminescense studies of the films employed 400 nm radiation for excitation of the Sm ions
4
6
present. The emission spectra showed signals arising from the
G
5/2- H
J
(J¼3/2, 7/2, 9/2) transitions,
C. Photoelectron spectroscopy
D. Luminescence
4
6
where the
G5/2- H3/2 transition has the highest intensity. The concentration dependence of the PL
intensity was also studied. A maximum PL intensity was observed with 10 mol% Sm content but then
diminished with higher Sm concentrations.
&
2010 Elsevier Ltd. All rights reserved.
1
. Introduction
Recently, a considerable amount of work has been reported on
the properties of rare earth-doped ZrO , such as ZrO :Eu [3,4],
ZrO :Er [5,6] and ZrO :Sm [1,7,8]. The lanthanide ions incorpora-
2
2
Zirconia-based oxide ceramics are attractive for a variety of
2
2
applications in areas such as optoelectronics devices [1]. Several
attributes influence the physical and chemical properties of these
materials, including crystal and amorphous structure, type and
level of dopant, surface morphology, composition, stoichiometry,
as well as the methodology of preparation.
tion into Zirconia materials can achieve special optical properties
due to structural modifications, thereby impacting the electronic
structure of the lattice host material. In the present study, we
2
report the formation of ZrO :Sm amorphous thin films, which
were generated via a photochemical reaction. In this method, thin
films of inorganic or organometallic precursors are irradiated,
thereby converted to amorphous films of metals or oxides,
depending on the reactions conditions. The development of this
method requires that the precursor complexes form stable
amorphous thin films upon spin-coating onto a suitable substrate
and photolysis of these films results in photoextrusion of the
ligands leaving the inorganic products on the surface (Eq. (1)).
In these last decades, there has been a considerable interest in
the lanthanide ions incorporated into host compounds due to
their luminescence properties. However, when the number of
non-radiative pathways increases, the fluorescence quantum
efficiency decreases considerably. One of the most important
non-radiative processes that every material has is the multi-
phonon relaxation by the vibration bands of the system. When the
frequency of this vibration band increases, the non-radiative
decay rate increases. Consequently, the quantum efficiency is
hv
O
2
nꢀ1
MðacacÞnðthin filmÞꢀꢀ!M
þnHacacꢀꢀ!M
x
O
y ðthin filmÞ þsub-products
ꢀ
1
reduced. The stretching frequency of ZrO
which is very small compared to that of other oxide hosts such as
TiO , Al or SiO [2]. This low phonon energy opens up the
possibility of more efficient luminescence of active ions incorpo-
2
is about 470 cm
,
ð1Þ
2
2
O
3
2
where M¼Zr or Sm; acac: acetylacetonate ligand.
The photochemistry of metal -diketonate complexes has been
b
2
rated into the ZrO matrix.
widely investigated [9], because they absorb strongly at readily
accessible parts of the UV spectrum (250–400 nm). In general, the
irradiation of the complexes with UV light (254 nm) leads to the
photoreduction of the complexes, upon LMCT (ligand-to-metal
charge transfer) excitation to form metals.
n
Corresponding author. Tel.: +56 42 253096; fax +56 42 253046.
E-mail address: gcabello@ubiobio.cl (G. Cabello).
0022-3697/$ - see front matter & 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.jpcs.2010.06.002

1
368
G. Cabello et al. / Journal of Physics and Chemistry of Solids 71 (2010) 1367–1372
In the case of lanthanide
b
-diketonate complexes, the charge
complex was deposited on n-type Si (1 0 0) by spin-coating from a
CH Cl solution. This resulted in the formation of a smooth,
transfer process between the lanthanide ion and the ligands
results when the easily oxidized ligand is bound to tervalent
lanthanide(III) ion which can be reduced to the divalent state [10].
2
2
uniform coating on the chip. The quality (uniformity, defects, etc.)
of the precursor films was determined by optical microscopy
(1000 ꢁ ), while the thickness was monitored by interferometry.
The FT-IR spectrum of the starting film was first obtained. The
irradiation of the films was carried out at room temperature using
two low-pressure Hg lamps (6 W, Rayonet RPR-2537A) in air,
until the FT-IR spectrum showed no evidence of the starting
material. Prior to analysis, the chip was rinsed several times with
dry acetone to remove any organic products remaining on the
surface. In order to obtain films of a specific thickness, successive
layers of the precursors were deposited by spin-coating and
irradiated as above. This process was repeated several times until
the desired thickness was achieved. Post-annealing was carried
out under a continuous flow of synthetic air at 750 1C for 2 h in a
programmable Lindberg tube furnace.
In the sense that the photo-deposition of the
b-diketonate
complexes with UV light generates a partial reduction of metal
ion, which is finally oxidized under aerated conditions.
In the present work we report the preliminary results on the
characterization of zirconium oxide thin films loaded with
samarium, generated by a photochemical reaction.
2
. Experimental
2
.1. General procedure
Fourier Transform Infrared spectra (FT-IR) were obtained with
ꢀ
1
4
cm
resolution in a Perkin Elmer Model 1605 FT-IR spectro-
photometer.
UV spectra were obtained with 1 nm resolution in a Perkin
3. Results and discussion
Elmer Model Lambda 25 UV–vis spectrophotometer.
3
.1. Photochemistry of Zr(IV) and Sm(III) acetylacetonate complexes
X-ray photoelectron spectra (XPS) were recorded on an
XPS–Auger Perkin Elmer electron spectrometer Model PHI 1257,
which included an ultra-high vacuum chamber, a hemispherical
electron energy analyzer and an X-ray source providing unfiltered
We have previously reported the solid state photochemistry of
the Zr(acac)
spin-coating and irradiated under air with a 254 nm UV source,
obtaining thin films of ZrO [11]. In order to evaluate the
photoreactivity of Sm(acac) complex, thin films of the Sm(acac)
3
4
complex films. They were deposited on Si(1 0 0) by
K
a
radiation from its Al anode (h
n¼1486.6 eV). The pressure of
the main spectrometer chamber during data acquisition was
maintained at ca 10 Pa. The binding energy (BE) scale was
calibrated by using the peak of adventitious carbon, setting it to
2
ꢀ
7
3
complex were irradiated and the photolysis was monitored by
FT-IR spectroscopy (Fig. 1). It was observed that the band at
1515 cm
2
84.8 eV. The accuracy of the BE scale was70.1 eV.
ꢀ
1
Atomic force microscopy (AFM) was performed in a Nanoscope
approx. associated with the carbonyl group of the
IIIa (Digital Instruments, Santa Barbara, CA) in contact mode. Film
thickness was determined using a Leica DMLB optical microscope
with a Michelson interference attachment.
ligand, decreased in intensity and after 24 h of irradiation only
minimal absorptions in the infrared spectrum remained. These
results suggest that the diketonate groups on the precursor
material are photodissociated on the surface, forming volatile
products which are partially desorbed.
Solid state photolysis was carried out at room temperature
under a low-pressure Hg lamp (
l¼254 nm) equipped with two
6
W tubes in an air. Progress of the reactions was monitored by
determining the FT-IR spectra at different time intervals, follow-
ing the decrease in IR absorption of the complexes.
2
3.2. Characterization of ZrO :Sm photodeposited thin films.
The substrates for deposition of films were borosilicate glass
For the deposition of ZrO
with different proportions of the Sm(acac)
0 mol%) were spin-coated on the appropriate substrate and the
2
:Sm thin films, solutions of Zr(acac)
4
2
microslides (Fischer, 2 ꢁ 2 cm ) and n-type silicon (100) wafers
3
complexes (10, 30 and
2
(
1 ꢁ 1 cm ) obtained from Wafer World Inc, Florida, USA.
5
Photoluminescense (PL) emission spectra measurements were
carried out in a multifrequency phase fluorometer (K2, ISS Inc.,
Urbana, Champaign, IL, USA) with a L-type setup. Excitation was
done with a 400 W UV Xe arc lamp, and the UV light passed
through a monochromator set to 400 nm. The measurements
were done at room temperature.
1
.8
1
515 cm-1
1.6
1.4
1.2
1.0
2
.2. Preparation of amorphous thin films
The precursors Zr(IV) and Sm(III) acetylacetonate complexes
were purchased from Aldrich Chemical Company and thin films
were prepared by the following procedure: A silicon chip was
placed on a spin coater and rotated at a speed of 1500 RPM.
2 2
A portion (0.1 ml) of a solution of the precursor complex in CH Cl
was dispensed onto the silicon chip and allowed to spread. The
motor was then stopped after 30 s and a thin film of the complex
remained on the chip. The quality of the films was examined by
optical microscopy (1000 ꢁ magnification).
0.8
0.6
1
000
1200
1400
Frequency (cm )
1600
1800
2000
2.3. Photolysis of complexes as films on Si (1 0 0) surfaces
-1
All photolysis experiments were done following the same
Fig. 1. FT-IR spectral changes associated with photolysis for 4 h of a Sm(acac)
3
procedure. A typical experiment was done as follows: A film of the
film deposited on Si (1 0 0).

G. Cabello et al. / Journal of Physics and Chemistry of Solids 71 (2010) 1367–1372
1369
thin films were irradiated until minimal absorptions in the
infrared spectrum from the complexes were observed.
to contamination from the environment rather than organic
residue from the organic raw materials [14].
The XPS spectra (Fig. 2) showed that the Zr 3d was composed of
two peaks with binding energy of 182.0 eV (Zr 3d5/2) and 185.5 eV
(Zr 3d3/2). The latter is usually disregarded, since almost all published
data refers to the 3d5/2 state. The observed binding energy of 182.1 eV
3
.2.1. XPS analysis
The elemental composition of the thin films was analyzed by
XPS in order to investigate their chemical nature. Fig. 2 presents
the XPS spectrum in the range of 0–1200 eV binding energy of as-
deposited and annealed samples. This survey spectrum shows
lines from Zr, O, and Sm, as well as a small amount of carbon,
which can be attributed to an organic residue from organic raw
precursors. After annealing at 750 1C it is found that a partial
elimination of this residual carbon occurs.
2
for Zr 3d5/2 can be assigned to ZrO [15,16]. After annealing at 750 1C,
the binding energy for Zr 3d5/2 was 181.9 eV.
The O 1s peak positions are at about 530 eV. (Fig. 3a) The high
resolution spectrum indicates that there are at least two chemical
states, including lattice oxygen (O
L
at 529.8 eV) and adsorbed
oxygen (Oads at 531.7 eV). The O 1s is mainly attributed to the
L
contribution of Zr–O bonds in the lattice and the Oads 1s is close to
the O–H bonds from adsorbed water molecules [17]. The peak
attributed to the hydroxyl group (OH) finally weakened
significantly after annealing at 750 1C.
The Sm 3d5/2 core level can be fitted with two subpeaks
(Fig. 3b), centered at 1083.3 eV (67.4%) and 1079.2 eV (32.6%) for
as-deposited films and 1083.0 eV (80.5%) and 1079.7 eV (19.6%)
for annealed films. The Sm 3d5/2 subpeak appearing at 1083 eV is
Other authors, working with metal-organic chemical vapor
deposition (MOCVD), have reported that metal
as Zr(acac) require high substrate temperatures (4600 1C) for
oxide growth and this may result in carbon incorporation [12,13].
On the other hand, Samarium -diketonates complexes such as
Sm(DPM)
b-diketonates such
4
b
3
(DPM¼2,2,6,6-tetramethyl-3,5-heptanedionate) have
been used as metal-organic precursors in aerosol-assisted metal-
organic chemical vapor deposition method (AA-MOCVD). In this
case, a small amount of carbon has been found on the surfaces due
3
+
assigned to the Sm
states and the subpeak at 1079 eV is
2
+
associated to the Sm states. Similar values have been reported
by other authors [18–20]. In summary, our results show a mixture
of two Sm oxidation states for as-deposited and annealed films.
3.2.2. Film morphology
AFM was used to study the morphology of photodeposited
films and the results are summarized in Table 1. Fig. 4 shows the
AFM micrographs. The as-deposited films have a non-uniform
rough surface without structural order, which is characteristic of
an amorphous deposit, with rms values increasing slightly with
the amount of Sm present in the films. After these films were
annealed at 750 1C for 2 h, rms values decrease significantly and a
more regular surface can be observed.
This reduction in roughness is due to the fact that a great part
of the sub-products generated during photolysis are eliminated
partially from the surface as a result of thermal treatment. This in
turn produces a redistribution of the deposits on the surface
generating a more compact and uniform film.
(
b)
a)
(
1200
1000
800
600
400
200
0
2
3.3. Photoluminescence study of the ZrO :Sm thin films
Binding Energy (eV)
The Sm ions were excited using 400 nm radiation, which
Fig. 2. XPS survey spectrum of (a) an as-deposited and (b) annealed at 750 1C
6
4
2
ZrO :Sm thin films prepared by UV irradiation at 254 nm.
matches with the
H5/2- K11/2 electronic transition in Sm ion
O 1s
Sm 3d5/2
Sm3+
OL
Sm2+
Oads
5
36
534
532
530
528
526
524
1088
1084
1080
1076
1072
Binding Energy (eV)
Binding Energy (eV)
3
+
L
Fig. 3. High resolution spectra: (a) O 1s, where O is lattice oxygen and Oads is adsorbed oxygen and (b) Sm 3d core level XPS spectra: fitted with two subpeaks of Sm and
2
+
Sm states.

1
370
G. Cabello et al. / Journal of Physics and Chemistry of Solids 71 (2010) 1367–1372
[
21,22]. Similar values of excitation have been reported in other
Photoluminescence emission spectra were measured in the
range of 450–800 nm. They are shown in Figs. 6 and 7. Three
characteristic emission bands have been reported to be at 560 nm
(green), 600 nm (orange) and 650 nm (red). They are assigned to
studies [21,23–25]. The excitation spectra (Fig. 5) were obtained
by monitoring the emission related to the band at 532 nm. It can
be seen that the spectra mainly consist of an intense and
broadband in the interval range between 390 and 410 nm and
another band situated at 380 nm. These bands indicate that the
samarium ions are located in an amorphous matrix.
4
6
3+
the G5/2- H
9/2, respectively [21,23,25].
J
transitions of the Sm ions, where J¼5/2, 7/2 and
The positions and intensity of the peaks correspond to different
PL mechanisms. The three Sm emission bands have been frequently
observed in various host matrices and have usually assigned to the
4
transitions from the first excited level
G5/2 to the ground state
Table 1
6
AFM results for ZrO
2
:Sm thin films: Rms (nm) and maximum height (nm).
H
J
levels. These three emission bands of Sm resulted following
non-radiative energy transfers from the ZrO host to the Sm ions
2
Thin Films
10 mol% Sm
30 mol% Sm
50 mol% Sm
which was followed by radiative Sm emission processes.
In our case, we have observed two broandbands centered at
533 and 600 nm and a shoulder at 646 nm. These signals can be
As-deposited
34.13 (224.6)
1.739 (21.54)
45.18 (283.1)
1.961 (17.67)
50.22 (315.5)
2.713 (18.79)
Annealed at 750 1C
4
6
4
6
4
6
assigned to the
G5/2- H3/2 [26], G5/2- H7/2 and G5/2- H9/2
Values in parenthesis show Rmax maximum height (nm).
transitions [21,27–29], respectively.
0
.2
1
2
0.4
0
.6
3
4
0.8
μm
μm
0
.2
1
2
0.4
0
.6
3
4
0.8
μm
μm
0
.2
1
2
0.4
0
.6
3
4
0.8
μm
μm
Fig. 4. AFM images of Sm loaded zirconium oxide films with: (a) as-deposited 10 mol% Sm, (b) annealed 10 mol% Sm, (c) as-deposited 30 mol% Sm, (d) annealed 30 mol%,
e) as-deposited 50 mol% Sm, and (f) annealed 50 mol% Sm.
(

G. Cabello et al. / Journal of Physics and Chemistry of Solids 71 (2010) 1367–1372
1371
6
5
4
3
2
1
00
00
00
00
00
00
0
The fine structure can be explained by taking into account that
6
the
J
H levels are split in the crystal field into 2J+1 sublevels,
as-deposited 10% mol Sm
annealed 10 % mol Sm
3
+
which clearly demonstrate that Sm ions are placed in a quite
regular environment, contrary to the situation encountered in
amorphous matrices, where displaced emissions can appear
corresponding to another transition type, besides the commonly
known types.
Fig. 6 shows the dependence of the PL spectra on samarium
2
concentration of as-deposited ZrO thin films. It is possible to
observe that the intensity at 533 nm reaches a maximum when
the concentration is 10 mol% Sm and decreases rapidly with
further increase in Sm concentration, probably due to concentra-
tion quenching (self-quenching) [27].
2
The PL spectra of ZrO :Sm annealed at 750 1C are shown in
unloaded ZrO2
Fig. 7. Two bands centered at 532 and 598 nm and a small
shoulder at 646 nm can be observed. When the concentration of
samarium increases, the emission intensity decreases. Besides,
the emission signal of annealed samples is lower in comparison
with the signal from as-deposited samples. A possible explanation
of the lower intensity is the fact that surface reconstruction
of the annealed films may cause the formation of some clusters of
320
340
360
380
400
420
Wavelength (nm)
2
Fig. 5. Excitation spectra of as-deposited and annealed ZrO loaded with 10 mol%
Sm thin films.
3
+
3+
Sm
ions, which leads to concentration quenching of Sm
luminescence.
9
8
7
6
5
4
3
2
1
00
00
00
00
00
00
00
00
00
0
On the other hand, it has been reported [30] the annealing
samples at high temperature decrease the excitation efficiency
and corresponding emission due to the loss of water within the
interlayer or surface of the films, due to the water molecules in
the interlayer or surface of the films can act as ‘‘water-bridge’’ to
λ
= 400 nm
ex
1
0% mol Sm
3+
30% mol Sm
enhance the bonding state of Sm ions with O–Zr of the material
host and thus improve the energy transfer process. When the
films are annealed, the host band gap excitation efficiency
decreases because the ‘‘water-bridge’’ is destroyed. When the
films are further annealed at 750 1C, the host band gap excitation
suddenly disappears and the luminescence quenches. In our case
the results for XPS confirm the presence of oxygen weakly
adsorbed attributed to groups OH of water molecules that
diminish significantly after annealing at 750 1C.
We think that the nature of defects centers in doped zirconia
influence the optical properties of these films. For example, the
excitation maximum (400 nm, 3.1 eV) appeared in our samples at
a lower energy than the band gap reported for the zirconia matrix
50% mol Sm
unloaded ZrO2
4
50
500
550
600
650
700
Wavelength (nm)
(
ꢂ5.0 eV) [1,11]. The energy level of these defects is critical to the
Fig. 6. Photoluminescence spectra of as-deposited ZrO
2
loaded with Sm thin films,
energy transfer process because if it is lower in energy than
emitting state of the lanthanide ion, no sensitized luminescence
can be observed. The energy level of the emitting state of
excited at 400 nm.
4
4
3
3
2
2
1
1
00
50
00
50
00
50
00
samarium ( G5/2) approximately 2.3 eV and this is the lower state
λ
= 400 nm
ex
than the energy level of defects of material host. It can, therefore,
be proposed that the energy of zirconia defects is not below this
value.
We propose a modified model based on the model given by
Frindell et al. [31] and similar to the one proposed by other
authors [32,33] for the energy transfer in this system, which
involves relaxation from defect states on zirconia before the
energy is transferred to the samarium ion. Fig. 8 shows: (1) an
energy level diagram which shows light being absorbed by defects
10% mol Sm
3
0% mol Sm
50% mol Sm
2
from ZrO host, (2) followed the non-radiative energy transfer
3
+
process from ZrO
2
defect to Sm
process of Sm ion.
Another mechanism proposed is (1) the excitation energy at
400 nm produce absorption by light corresponding to the
level and (3) the emission
3
+
50
unloaded ZrO2
6
4
3+
0
H
5/2- K11/2 transition of Sm
moves to the lowest excited energy level ( G5/2) through relaxation,
3) and finally the emission due to transitions from one of the
ion, (2) and the electron state
4
450
500
550
600
650
700
(
Wavelength (nm)
4
6
6
3+
excited state G5/2 to the ground levels of H3/2 and H7/2 from Sm
.
The emission spectra of divalent samarium ions, in the spectral
range from 685 to 775 nm, that are mainly attributed to
2
Fig. 7. Photoluminescence spectra of annealed ZrO loaded with Sm thin films,
excited at 400 nm.

1
372
G. Cabello et al. / Journal of Physics and Chemistry of Solids 71 (2010) 1367–1372
4
6
3+
been assigned to
G
5/2- H
J
transitions of the Sm
ions. A
maximum PL intensity is observed at low Sm concentrations,
about 10 mol%, and then the intensity falls with increasing
concentration. A more detailed study is required to determine
photoluminescent properties of the obtained films to further
explore this energy transfer system and elucidate the mechanism
for the apparent concentration quenching, as well as verify the
proposed mechanism, which involves light absorption and
emission by matrix defects.
Acknowledgments
Fig. 8. Proposed mechanism of photoluminescence process in ZrO
2
:Sm thin films:
The authors are grateful to the financial support of the
FONDECYT (National Fund for Scientific and Technological
Development), Chile, Grant no. 1060486 and Direcci o´ n de
Investigaci o´ n de la U. del B ı´ o-B ı´ o, DIUBB proyect. Grant no.
(
1) excitation process, (2) non-radiative energy transfer process and (3) emission
3
+
process of Sm
.
5
7
intraconfigurational
D
0
- F
J
(J¼0,1,2,3) [27,34]. We have not
092509 3/R.
seen any emission signal in the range of 650–800 nm. Therefore,
3
+
we assigned the observed emission signals mainly to Sm ions.
2
+
References
On the other hand, the percentage of Sm
present in the
samples only reached 32% and 20% for as-deposited and annealed
films respectively, according to information provided by the XPS
analysis, and that probably do not contribute to new lumines-
cence emission.
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(
[
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[
[
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of photons (400 nm) by the nature of defects centers of ZrO
2
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6
4
the absorption corresponding to the
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H5/2- K11/2 transition of
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3
+
5
D
0
level
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2
+
corresponding to Sm ion, which essentially correspond to non-
radiative transitions. (Fig. 8).
[
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1
It has been reported that the incorporation of metal ions into
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[
[
[
ZrO
which subsequently generate new band gaps [35]. The effects that
dopants have on the performance of ZrO are mainly associated with
2
thin films produce impurity levels between the intrinsic bands,
2
modifying the microstructure as well as reducing the band gaps [35].
Depending on type and chemical states of metal ions and of intrinsic
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2
defects of the material host, the energy levels in ZrO varied. Various
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energy transfers between other materials such as the semiconduc-
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these emissions are strongly dependent on the characteristics of the
material host, which determine a variety of parameters such as
energy levels, energy transfer and non-radiative relaxation process
and also by the active lanthanide ion concentration, aspects that
deserve a subsequent study.
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[
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[
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4
. Conclusions
[
[
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tions of Zr(acac)
4
and Sm(acac)
3
complexes on silicon substrates
:Sm thin films. These films
lead to production of amorphous ZrO
2
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contain low concentrations of OH groups and show carbon
contamination attributed to the organic residue from organic
raw precursors, which can be eliminated or reduced by submit-
ting the deposits to a heat treatment, according to the information
we obtained from XPS. The surface characterization of these thin
films was performed using AFM, revealing that as-deposited
[
[
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[
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[
2
ZrO :Sm films have a rougher and irregular surface than
34] R. Stefania, A.D. Maiaa, E.E.S. Teotonioa, M.A.F. Monteiroa, M.C.F.C. Felintob,
thermally treated films. Photoluminescent properties have been
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