Selective methods
formation of nanoparticles
chalcogenide
semiconductors
May 2011, Oulu, Finland
MUSTAFA B.MURADOV
Baku State University
NanoCentre
E-mail: mbmuradov@gmail.com
http://napep.net
Z.Khalilov 23, Baku, AZ1148, AZERBAIJAN
NANOPARTICLES
New physical and chemical properties
Thermodynamic peculiarities
Opportunities of creation essentially new
materials and devices
Opportunity of controlling of physical and
chemical properties of materials
-By changing of nanoparticle size
-By changing of parameters core/shell structure
Selective methods of growth –
nanoscale engineering
Allow to operate the sizes of thin films and
particles at level of monomolecular layer
• Atomic-layered epitaxy- 1977 by Dr. Tuomo Suntola, at the
University of Helsinki in Finland
• Chemical assembly – Aleskovskiy V.B. Synthesis and stechiometry of solid
materials. L.: Nauka, 1976, 142p.
• Successful ion layered adsorption and reaction
(SILAR) -V.F.Nicolau,
Appl. of surface Sci. 22/23 (1985) 1061
.
Selective methods of growth - ALE
• Atomic-layered epitaxy(deposition)
-surface controlled, self-limiting method,
-nano structures from gaseous precursors,
-accurate and simple film thickness control,
• -sharp interfaces uniformity over large areas,
excellent conformality, good reproducibility,
• multilayer processing capability, and high film
qualities at relatively low temperatures.
Selective methods of growth – ALE
(ALD)
• reactant vapours are pulsed onto the
substrate alternately one at a time,
• All the process steps are saturative,
groups—saturatively forming a tightly
bound monolayer on the surface,
• film growth is self-limiting
• one cycle – maximum one monolayer
A schematic representation of the basic principle of the
ALE process showing the growth of ZnS film from ZnCl2 and H2S
Mikko Ritala, Markku Leskela, Nanotechnology 10 (1999) 19–24.
A schematic representation of the basic principle of the
ALE process showing the growth of ZnS film from ZnCl2 and H2S
Schematic of the Al2O3 ALD
process
Main Characteristic features of ALE –
one cycle of formation of
oxides
• 1) metal exposure,
• 2) purge,
• 3) oxidizing exposure,
• 4)purge
GROWTH RATE
Erin D. Robertson
Doctoral thesis, 2010
Dependence of Growth Rate from
Temperature
Growth Rate – Purge time
ALD WINDOW
Temperature window
• temperature process window can be
identified based on the constant growth rate
of the ALD process
• low temperatures - low growth rates
-necessary value of activation energy
-may be high growth rate as result of
condensation
Temperature window
• High temperatures can lead to the
decomposition of the ALD precursor or
desorption of the adsorbates before they
are reacted with the 2nd reactant
Main Characteristic features of ALE
1. Self-limiting growth process,
2. Separate dosing of reagents,
3. Processing temperature windows are
often wide
ALE Application
•
•
•
•
Chemichal modification of surface,
Controlling thickness of thin films,
processing porous substrates,
modify the surfaces of the porous substrates
•
•
•
•
•
•
[28] D.ucs.o C, Khanh N Q, Horv.ath Z, Barsony I, Utriainen M,
Lehto S, Nieminen M and Niinist.o L 1996 J. Electrochem.
Soc. 143 683
[29] Utriainen M, Lehto S, Niinist.o L, D.ucs.o C, Khanh N Q,
Horv.ath Z E, B.arsony I and P.ecz B 1997 Thin Solid Films
297 39
SILAR(successive ion layered adsorption and
reaction) or Ion-layered chemisorptions
(One cycle of formation)
• Adsorptions of cations on surface (volume)
of substrate
• Washing residue of electrolytes with the
solvent
• Adsorptions of anions on surface (volume)
of substrate
• Washing residue of electrolytes with the
solvent
SILAR - Process of growth
SILAR POSSIBILITY
• Thin films
-Semiconductors,
-Oxide of metals,
• Nanocomposites
-polymer inorganic nanoparticles
composites,
-porous materials and nanoparticles.
SILAR POSSIBILITY
• Nano Engineering,
-changing of physical properties,
-surface engineering,
Shell Preparation by SILAR
P. Reiss, M. Protie`re and L. Li, small 2009, 5, No. 2, 154–168
ZnO/CdS core/shell structures
• STEP1 - ZnO nanowire
arrays were grown by a
hydrothermal method,
• STEP2 - Successive ion
layer adsorption and
reaction
J.Joo, D.Kim, D.Yun Nanotechnology 21 (2010) 325604
SILAR - ZnO/CdS core/shell
structure
SEM&TEM images
PERSPECTIVE OF PREPERATION NANOSTRUCTURE
CdS
CuS
•Selective growth process
•Sharp boundary between
core&shell
Ion layered chemisorptions
Diffusion boundary between
core&shell
CdS
CuS transformation
process
Ion-exchange
Features of growth
• Opportunity of controlling structure and
stochiometric composition with the help of
changing thermodynamic parameters of
system
• Growth of structures in conditions of
local thermodynamic equilibrium
Thermodynamics of prosses
V.N.Maslov, M.B.Muradov,
• µ =µ
• µ -chemical potential of copper in
Cun
Cus
Cun
nanoparticles, µ - chemical potential of copper
in solutions
• µ=µ +kT lnC
C- concentration of solutions, T-temperature, µchemical potentials, µ -standard chemical
potentials of particles, k- Boltzmann constant
Cus
0
0
V.N.Maslov, M.B.Muradov and oth. Thermodynamic and kinetic futures of
growth thin films by ion layered chemisorptions. In book “Growth process of
semiconductor thin films and crystals”
Thin Films Growth
• Growth rate dependence
-concentration
-temperature
-pH
• Can we manage the structure of thin films?
- Concentration of anions and cations
- temperature
Temperature dependence thickness of CdS thin
films(dashed line) (Ge substrate) – for bulk CdST=1278K, for ZnS T=1430K
d,(Å)
500
T
400
d1
300
d2
200
d3
d4
100
0
400
500
550
600
650
700
800 T,(k)
Temperature dependence of angular orientation
microcrystallites (CdS/Ge)
Dependence of refractive of CdS
thin films from thickness and
growth condition
A.M.Kutepov, V.N.Maslov, V.S.Pervov, M.B.Muradov, Fractal growth
of cadmium sulfide films during ionic-layered chemisorption,Doklady
Akademii Nauk SSSR, 1989 v.304, №4, p.1900-1903(in Russian)
NANOCOMPOSITES
• Matrix (Polymer, Inorganic porous
materials)
• Active chemical groups for sorption of
cations or anions,
• Chemical modification of polymers or
other matrix for creating active chemical
groups
Materials for Creating of
Nanocomposites
• Polymers
-Polyvinyl alcohol,
-Gelatine,
• Semiconductor Nanoparticles
-CdS, CdSe, CuS
The transmission spectra of samples CdS:gelatin/glass, dashed line
after thermal annealing (T=90C, t=30min), d=30-200A, ∆E=0.7eV
E 

2

*
2
2m d
2
M.B. Muradov, A.A. Agasiyev, Formation of cadmium sulfide particles
in te volume of polimeric matrix., Pisma v Zhurnal Technicheskoy
Fiziki 1991,v.17, issue.13, p.54-57(in Russian).
SILAR - The change of refractive
index structure CdS:gelatin
M.B.Muradov, V.L.Smirnov, V.A.Karavanskii Patent USSR
N1448914, 1986;.
Dependence of (αhν)2 from hν; a)1 - 6, 2- 10,315cycles; b)1- 1, 2-4cycles of formation;
∆E=0.45eV; d≥11A
( h )
2
M.B.Muradov, G.M.Eyvazova,N.H.Darvishov,S.E.Bagirova Some
optical properties of nanoparticles copper sulphide, formed in
volume of a polymeric matrix, Transaction NAS Azerbaijan, ser.
Physical-mathematical and technical science, 2004,№5.
Cd(NO3)2 concentration is constant
5
(ahv)2
4
0,1molar
0,2
0,4
0,8
3
2
1
0
1
1,5
2
2,5
3
3,5
4
hv
M.B.MURADOV, G.M.EYVAZOVA, A. N. BAGIROV, The effect of solutions
concentrations on the optical properties of CdS nanoparticles formed
in the polymeric matrix, JOURNAL OF OPTOELECTRONICS AND ADVANCED
MATERIALS Vol. 9, No. 5, May 2007, p. 1411 - 1413
Na2S concentration is constant
CdS
5
4,5
(ahv)2
4
3,5
3
0,1molar
0,2
0,4
0,6
0,8
2,5
2
1,5
1
0,5
0
1
1,3
1,6
1,9
2,2
2,5
hv
2,8
3,1
3,4
3,7
4
CdS:gelatin – before thermal annealing
hνmax 30-2.3ev;15-2.48ev; 7&10-2.64ev
Exitation spe ctra, CdS:Ge latin
6.00
5.00
4.00
I,r.u.
7 cycle
10 cycle
3.00
15 cycle
30 cycle
2.00
1.00
0.00
1.50
2.00
2.50
3.00
3.50
hV, eV
M. B. MURADOV The influence of the type of polymer matrix on the
photoluminescence from cadmium sulfide nanoparticles,
OPTOELECTRONICS AND ADVANCED MATERIALS – RAPID COMMUNICATIONS
Vol. 2, No. 2, February 2008, p. 85 - 88
CdS:gelatin after thermal annealing
hνmax 30-2.34ev; 15-2.48ev;10-2.58ev;7&5 – 2.64ev;3-2.67ev
Excitation spectra CdS:Gelatin,
after annealing
120
100
30 cycle
80
I,%
15 cycle
10 cycle
60
7 cycle
5 cycle
40
3 cycle
20
0
1
2
3
hv, eV
4
PL, CdS-gelatin, emission spectra- before thermal annealing
hνmax: 7&10 -1.44ev, 15-1.41ev, 30-1.38ev
Emission spectra, CdS: Gelatin
600
500
I,rel.un.
400
7 cycle
10 cycle
300
15 cycle
30 cycle
200
100
0
1
1.2
1.4
1.6
hV, eV
1.8
2
PL, CdS-gelatin, emission spectra- after thermal annealing
hνmax 3-1.61ev, 5-1.56ev, 7-1.44ev, 10 -1.41ev, 15&30-1.37ev
Emission Spectra
600
500
400
30
rel.unit
15
10
300
7
5
3
200
100
0
0
0.5
1 E,(eV)
1.5
2
2.5
CdS:PB Spectra of excitation,
hν =2.82 ev
max
PB:CdS
120
low
average
high
100
I, %
80
60
40
20
0
0
1
2
3
E, hv
4
1-high, 2-mid, 3-low level
CdS:PB before thermal annealing
hν =1.71 ev
max
PL-emission spectra
hν =1.71 ev
max
CdS polybutadien
120
100
before thermal
annealing
I%
80
after thermal
annealing
60
40
20
0
0,5
0,7
0,9
1,1
1,3
E,(eV)
1,5
1,7
1,9
2,1
Photoluminescence
• Intensity of PL depends from
- type of matrix,
- Annealing temperature,
• character of interaction
nanoparticles-polymer
CONCULUSION
• Self-limited methods are perspective
tools for nanotechnology,
• Nanoscale engineering,
• Surface modification,
• New methods of formation of
complex nanomaterials
THANKS
My Colleges:
Dr.G.Eyvazova,
Dr.N.Darvishov
Mrs. S.Bagirova.
My Students:
Azer Bagirov,
Yashar Azizian,
Nurane Huseynova