PbSe quantum dots (QDs) were synthesed in fluorophosphate glass and their absorption and lumines-cence properties were investigated. The effect of the duration of the heat treatment on the spectral-luminescent properties was considered. The average diameter of the synthesized quantum dots has been calculated.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3536

Abdrshin, A.N.

Aseev, V.A.

Kolobkova, E.V.

Nikonorov, N.V.

Poliakova, A.V.

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 2 No 4, 04NAESP06(2pp) (2013)   2304-1862/2013/2(4)04NAESP06(2) 04NAESP06-1  2013 Sumy State University Optical Properties of PbSe Qantum Dots Doped in Fluorophosphate Glasses  A.V. Poliakova*, E.V. Kolobkova†, A.N. Abdrshin‡, N.V. Nikonorov§, V.A. Aseev**  Saint-Petersburg National Research University of Information Technologies, Mechanics and Optics, 49, Kronverskiy Pr., 197101 Saint Petersburg, Russia  (Received 18 June2013; published online 30 August 2013)  PbSe quantum dots (QDs) were synthesed in fluorophosphate glass and their absorption and lumines-cence properties were investigated. The effect of the duration of the heat treatment on the spectral-luminescent properties was considered. The average diameter of the synthesized quantum dots has been calculated.  Keywords: Fluorophosphate glass, PbSe, Quantum dots.   PACS numbers: 42.70.Qs, 78.67.Hc, 87.07.Ta                                                    * avpoliakova@bk.ru † kolobok106@rambler.ru ‡ myltitabs@mail.ru § nikonorov@oi.ifmo.ru ** aseev@oi.ifmo.ru 1. INTRODUCTION  At the moment, there is considerable interest in the creation of high-performance passive Q-switcher  for range of transparency of fiber telecommunications networks. All technical solutions related to equipment fiber links require a simple and compact laser systems. A special place among occupy the solid-state lasers, operating in the Q-switching mode. These lasers can get nanosecond and picosecond pulses of light high power. Q-switching methods are quite diverse. One of these methods, widely used, is a Q-switched with a passive shutter (phototropic shutter bleachable filter, saturable absorber). Phototropic media can reversibly change the value of the absorption coefficient under the influence of powerful light beams. This is the basis for this method. This method in combination with a sufficiently high radiation parameters, is easy to install in the valve cavity and does not require the use of additional sources of supply. Nowadays more than one type of solid-state satura-ble absorbers for infrared laser range 1.3-1.5 microns (crystals with color centers, crystals and glasses doped with rare-earth or transition metal single-or multi-layer epitaxial semiconductor saturable absorber (SESAM) are used. However such absorbers have sig-nificant disadvantages which include rapid aging (crys-tals with color centers), a large effective relaxation time and / or the need for focusing of intracavity to obtain the required levels of illumination (glass doped with erbium), or high cost associated with the complex-ity of the technology (SESAM). levels (glass doped with erbium), or high cost associated with the complexity of the technology (SESAM). Glasses containing quantum dots are a promising material for passive Q-switching and mode locking, since the position of the absorption peaks is determined by the size of the quantum dot, which gives the opportunity to "tune" spectral domain of optical nonlinearity which observed in the region of the first exciton absorption peak. Moreover, these glasses with quantum dots have advantages which compared with other materials for passive intracavity modulators and Q synchronizers modes due to a sub-stantial gain in cost, because their manufacturing methods can use standard glass melting. The main requirement for materials of saturable absorbers is a narrow distribution of quantum dots (QDs) in size (ΔR / R ~ 10%, R – quantum dot size), resulting in a narrow first excitonic peak corresponding to the first exciton transition, and uniform distribution of the quantum dots in the amount of glass. It should be noted that the temperature-time regimes of formation of quantum dots in fluorophosphate glasses much softer than in silicate glasses, with their relative proximity to the glass transition temperatures (450-480°C for silicate and 425° C for fluorophosphate). This is due to differ-ent stroke dependence of viscosity on temperature for specified classes of glasses. It should also be noted that the glass with PbSe quantum dots can be used in a broader spectral range than with PbS, due to differences in the values of the exciton Bohr radius (20 nm and 46 nm PbS for PbSe) and a bandgap (Eg PbSe  0.29 eV Eg PbS  0,41 eV at 300K). Thus, to date, glass, studied in the work are quite promising systems prone to the formation of RbSe - quantum dots.  2. EXPERIMENTAL PROCEDURES  The samples of the fluorophosphate glasses of Na2О-P2O5-Ga2O3-AlF3-ZnO(Se)-PbF2 with an equal concentration of the semiconductor phase PbSe were inverstigated. The synthesis was performed in closed glasscarbon crucible at the temperature of 950 1000°C under the argon atmosphere; the duration of the syn-thesis was 40 min. These conditions of the synthesis allowed receiving glasses with high transmission coeffi-cient in 0.3 3 m wavelength region. The glass melt  A.V. POLIAKOVA, E.V. KOLOBKOVA , A.N. ABDRSHIN ET AL. PROC. NAP 2, 04NAESP06 (2013)   04NAESP06-2 was processed between two cold glass-carbon plates. The tempered glasses had a maximum thickness of 2 mm. For the synthesis of quantum dots samples were subjected to heat-treatment at 415°C for 20-120 min. The temperature of heat-treatment was indicated by DSC STA 449F1 Nietzsche. The absorption specter was recorded on Varian Cary 500 on Varian Cary 500 spec-trophotometer in the range 300-3300 nm. Photolumi-nescence spectra were measured using the 980 nm excitation sources from a laser diodes. The  RED-Wave-NIRX fiber optic spectrometers were used to recorded photoluminescence specter.  All measurements were performed at room temperature.   3. RESULTS   The parent glass was transparent and their color was light-yellow. After heat-treatment at 415 ° for 40-120 min the color gradually changed. The grade of coloration (from light brown to black) of samples was depended from duration of the heat-treatment. Fig. 1 shows the absorption spectra of the glass heat-treated at room temperature. The clear first excitonic absorp-tion peak in the near-infrared region for each of the samples was observed. Also the blue-shifted (their peak positions moved to the short wavelength side) com-pared to the location of the band-gap energy of the bulk material was demonstrated. In addition, with increas-ing heat-treatment times the peak positions moved to the long wavelength side (red-shift), indicating the strong quantum confinement effect in PbSe QDs.    Fig. 1 – Absorption spectra of PbSe QDs in fluorophosphate glasses  after heat-treatment during different duration at 415°C  Also photoluminescence was achieved in 1.1-1.6 m wavelength region after heat-treatment for 20-60 min. (table 1). The photoluminescence was not found after heat-treatment for 90-120 min.  4. DISCUSSION  The average diameters of the QDs were computed  using  the following fitting  formula [1] from the meas-ured band-gap energies :   210 0105 0 2655 0 0667( ) ( ) .. . .g gE D ED D (4.1)  where, D is diameter of PbSe QDs (in nm). Eg(D) is the effective band-gap energy( in eV), calculated from the first exsitonic absorption peak. And Eg(∞) is the band-gap energy of the bulk PbSe semiconductor (0.29 eV). The sizes of PbSe QDs are presented in table 1.   Table 1 – Optical properties and sizes of PbSe QDs in fluoro-phosphate glasses. (D  calculated average diameter, abc  absorption peak position, FWHM full width at half maximum of absorption peak, PH  peak wavelength of photolumines-cence)  Heat-treatment time (min) D( nm) abc (nm)  FWHM, cm-1 PH,(nm) 40  4.1 1179 1136 1347 60  5.2 1429 1002 1592 90  7.8 1882 564  120  9.1 2082 518   As shown, average diameter of QDs increased with magnification duration of heat-treatment.   As shown in table 1, the FWHM (full width at half maximum) of absorption peak decreased with increased heat-treatment time. Probably it means, that the vari-ance of Qds sizes decreased.  5. CONCLUSIONS  Lead selenide quantum dots were synthesized in fluorophosphate glasses, and  their optical properties were investigated. QDs PbSe were precipitated through the thermal treatment  at 415°C for 40-120 min. The position of the first exsitonic peak  situated in 0.9-2.1 m wavelength range and depended from duration treatment and The intensive photoluminescence was achieved in 1.1-1.6 m region for samples, which treatment time was 40 - 60 min. The maximum diame-ter of  synthesized QDs PbSe was 9.1 nm.  AKNOWLEDGEMENTS  This work was supported by grant from Russian Foundation for Basic Research (nos. 13-08-1288).   REFERENCES  1. G.Allan, C. Delerue, Phys. Rev. B 70 (2004) 245321.   

Optical Properties of PbSe Qantum Dots Doped in Fluorophosphate Glasses

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  
NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 2 No 4, 04NAESP06(2pp) (2013) 
 
 
2304-1862/2013/2(4)04NAESP06(2) 04NAESP06-1  2013 Sumy State University 
Optical Properties of PbSe Qantum Dots Doped in Fluorophosphate Glasses 
 
A.V. Poliakova*, E.V. Kolobkova†, A.N. Abdrshin‡, N.V. Nikonorov§, V.A. Aseev** 
 
Saint-Petersburg National Research University of Information Technologies, Mechanics and Optics, 49, Kronverskiy 
Pr., 197101 Saint Petersburg, Russia 
 
(Received 18 June2013; published online 30 August 2013) 
 
PbSe quantum dots (QDs) were synthesed in fluorophosphate glass and their absorption and lumines-
cence properties were investigated. The effect of the duration of the heat treatment on the spectral-
luminescent properties was considered. The average diameter of the synthesized quantum dots has been 
calculated. 
 
Keywords: Fluorophosphate glass, PbSe, Quantum dots. 
 
 PACS numbers: 42.70.Qs, 78.67.Hc, 87.07.Ta 
 
 
                                                 
* avpoliakova@bk.ru 
† kolobok106@rambler.ru 
‡
 myltitabs@mail.ru 
§
 nikonorov@oi.ifmo.ru 
**
 aseev@oi.ifmo.ru 
1. INTRODUCTION 
 
At the moment, there is considerable interest in the 
creation of high-performance passive Q-switcher  for 
range of transparency of fiber telecommunications 
networks. All technical solutions related to equipment 
fiber links require a simple and compact laser systems. 
A special place among occupy the solid-state lasers, 
operating in the Q-switching mode. These lasers can 
get nanosecond and picosecond pulses of light high 
power. Q-switching methods are quite diverse. One of 
these methods, widely used, is a Q-switched with a 
passive shutter (phototropic shutter bleachable filter, 
saturable absorber). Phototropic media can reversibly 
change the value of the absorption coefficient under the 
influence of powerful light beams. This is the basis for 
this method. 
This method in combination with a sufficiently high 
radiation parameters, is easy to install in the valve 
cavity and does not require the use of additional 
sources of supply. 
Nowadays more than one type of solid-state satura-
ble absorbers for infrared laser range 1.3-1.5 microns 
(crystals with color centers, crystals and glasses doped 
with rare-earth or transition metal single-or multi-
layer epitaxial semiconductor saturable absorber 
(SESAM) are used. However such absorbers have sig-
nificant disadvantages which include rapid aging (crys-
tals with color centers), a large effective relaxation 
time and / or the need for focusing of intracavity to 
obtain the required levels of illumination (glass doped 
with erbium), or high cost associated with the complex-
ity of the technology (SESAM). levels (glass doped with 
erbium), or high cost associated with the complexity of 
the technology (SESAM). Glasses containing quantum 
dots are a promising material for passive Q-switching 
and mode locking, since the position of the absorption 
peaks is determined by the size of the quantum dot, 
which gives the opportunity to "tune" spectral domain 
of optical nonlinearity which observed in the region of 
the first exciton absorption peak. Moreover, these 
glasses with quantum dots have advantages which 
compared with other materials for passive intracavity 
modulators and Q synchronizers modes due to a sub-
stantial gain in cost, because their manufacturing 
methods can use standard glass melting. The main 
requirement for materials of saturable absorbers is a 
narrow distribution of quantum dots (QDs) in size (ΔR / 
R ~ 10%, R – quantum dot size), resulting in a narrow 
first excitonic peak corresponding to the first exciton 
transition, and uniform distribution of the quantum 
dots in the amount of glass. It should be noted that the 
temperature-time regimes of formation of quantum 
dots in fluorophosphate glasses much softer than in 
silicate glasses, with their relative proximity to the 
glass transition temperatures (450-480°C for silicate 
and 425° C for fluorophosphate). This is due to differ-
ent stroke dependence of viscosity on temperature for 
specified classes of glasses. 
It should also be noted that the glass with PbSe 
quantum dots can be used in a broader spectral range 
than with PbS, due to differences in the values of the 
exciton Bohr radius (20 nm and 46 nm PbS for PbSe) 
and a bandgap (Eg PbSe  0.29 eV Eg PbS  0,41 eV at 
300K). 
Thus, to date, glass, studied in the work are quite 
promising systems prone to the formation of RbSe - 
quantum dots. 
 
2. EXPERIMENTAL PROCEDURES 
 
The samples of the fluorophosphate glasses of 
Na2О-P2O5-Ga2O3-AlF3-ZnO(Se)-PbF2 with an equal 
concentration of the semiconductor phase PbSe were 
inverstigated. The synthesis was performed in closed 
glasscarbon crucible at the temperature of 950 1000°C 
under the argon atmosphere; the duration of the syn-
thesis was 40 min. These conditions of the synthesis 
allowed receiving glasses with high transmission coeffi-
cient in 0.3 3 m wavelength region. The glass melt 
 A.V. POLIAKOVA, E.V. KOLOBKOVA , A.N. ABDRSHIN ET AL. PROC. NAP 2, 04NAESP06 (2013) 
 
 
04NAESP06-2 
was processed between two cold glass-carbon plates. 
The tempered glasses had a maximum thickness of 2 
mm. For the synthesis of quantum dots samples were 
subjected to heat-treatment at 415°C for 20-120 min. 
The temperature of heat-treatment was indicated by 
DSC STA 449F1 Nietzsche. The absorption specter was 
recorded on Varian Cary 500 on Varian Cary 500 spec-
trophotometer in the range 300-3300 nm. Photolumi-
nescence spectra were measured using the 980 nm 
excitation sources from a laser diodes. The  RED-Wave-
NIRX fiber optic spectrometers were used to recorded 
photoluminescence specter.  All measurements were 
performed at room temperature.  
 
3. RESULTS  
 
The parent glass was transparent and their color 
was light-yellow. After heat-treatment at 415 ° for 40-
120 min the color gradually changed. The grade of 
coloration (from light brown to black) of samples was 
depended from duration of the heat-treatment. Fig. 1 
shows the absorption spectra of the glass heat-treated 
at room temperature. The clear first excitonic absorp-
tion peak in the near-infrared region for each of the 
samples was observed. Also the blue-shifted (their peak 
positions moved to the short wavelength side) com-
pared to the location of the band-gap energy of the bulk 
material was demonstrated. In addition, with increas-
ing heat-treatment times the peak positions moved to 
the long wavelength side (red-shift), indicating the 
strong quantum confinement effect in PbSe QDs. 
 
 
 
Fig. 1 – Absorption spectra of PbSe QDs in fluorophosphate 
glasses  after heat-treatment during different duration at 
415°C 
 
Also photoluminescence was achieved in 1.1-1.6 m 
wavelength region after heat-treatment for 20-60 min. 
(table 1). The photoluminescence was not found after 
heat-treatment for 90-120 min. 
 
4. DISCUSSION 
 
The average diameters of the QDs were computed  
using  the following fitting  formula [1] from the meas-
ured band-gap energies : 
  
2
1
0 0105 0 2655 0 0667
( ) ( ) .
. . .
g gE D E
D D
 (4.1) 
 
where, D is diameter of PbSe QDs (in nm). Eg(D) is the 
effective band-gap energy( in eV), calculated from the 
first exsitonic absorption peak. And Eg(∞) is the band-
gap energy of the bulk PbSe semiconductor (0.29 eV). 
The sizes of PbSe QDs are presented in table 1.  
 
Table 1 – Optical properties and sizes of PbSe QDs in fluoro-
phosphate glasses. (D  calculated average diameter, abc  
absorption peak position, FWHM full width at half maximum 
of absorption peak, PH  peak wavelength of photolumines-
cence) 
 
Heat-treatment 
time (min) 
D( nm) abc (nm)  FWHM, 
cm-1 
PH,(nm) 
40  4.1 1179 1136 1347 
60  5.2 1429 1002 1592 
90  7.8 1882 564  
120  9.1 2082 518  
 
As shown, average diameter of QDs increased with 
magnification duration of heat-treatment.   
As shown in table 1, the FWHM (full width at half 
maximum) of absorption peak decreased with increased 
heat-treatment time. Probably it means, that the vari-
ance of Qds sizes decreased. 
 
5. CONCLUSIONS 
 
Lead selenide quantum dots were synthesized in 
fluorophosphate glasses, and  their optical properties 
were investigated. QDs PbSe were precipitated through 
the thermal treatment  at 415°C for 40-120 min. The 
position of the first exsitonic peak  situated in 0.9-
2.1 m wavelength range and depended from duration 
treatment and The intensive photoluminescence was 
achieved in 1.1-1.6 m region for samples, which 
treatment time was 40 - 60 min. The maximum diame-
ter of  synthesized QDs PbSe was 9.1 nm. 
 
AKNOWLEDGEMENTS 
 
This work was supported by grant from Russian 
Foundation for Basic Research (nos. 13-08-1288). 
 
 
REFERENCES 
 
1. G.Allan, C. Delerue, Phys. Rev. B 70 (2004) 245321. 
  


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Optical Properties of PbSe Qantum Dots Doped in Fluorophosphate Glasses

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