Characterization of different dopants in TiO2 Structure by Pulsed Laser Deposition
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Transcript of Characterization of different dopants in TiO2 Structure by Pulsed Laser Deposition
Characterization of different dopants in TiO2 Structure by
Pulsed Laser Deposition
Supervised by
Prof.Dr. Adawiya J.Haider Prof.Dr. Raad M.S.Al-Haddad
UNIVERSITY OF TECHNOLOGY
A thesis submitted By
Khaled Z.Yahya
يم� ح� الر� من� ح� الر� الل�ه� م� ب�س�
ت�ن�ا ع�ل�م� ا �م إ�ال� ل�ن�ا �ل�م ع� �ال �ان�ك �ب�ح س' ال'وا� �ق
�أ�نت ��ن�ك ك�يم' إ �ال�ح ال�ع�ل�يم'
ال�ع�ظ�يم' الل�ه' �د�ق � ص
{٣٢البقرة }
PLD: Pulsed Laser Deposition The interaction of the laser beam with
the target resulting in evaporation of the surface layers.
The interaction of the laser beam with the evaporation materials causing the formation ofisothermal expanding plasma.
The expansion of the laser induced plasma with a rapid transfer of thermal energy of the species in plasma into kinetic energy.
Thin film growth.
Rotating target
Laser Pulsed
Substrate heater
Ejected Plume
Deposited
film
Why TiO2?
Titanium dioxide (TiO2) is a wide band gap (3.2) eV for anatase and 3 eV for rutile .
Titanium dioxide have high refractive index - up to 2.7 (at wavelength of 600nm)
Titanium dioxide good chemical resistance and high chemical stability.Titanium dioxide good sensitivity to poison gases. Titanium dioxide good photocatalysts.
3
TiO2 structure
Anatase Rutile Brockets
TiO2 gas sensor
• TiO2 based sensor are predominant solid-state gas sensors for domestic, commercial and industrial application.
• •Low cost• •Easy production • •Rigid construction• •Compact size• •Simple measuring electronics
Aim of the work The aim of this work is to reveal specific properties of TiO2
nanostructure prepared by pulsed laser deposition technique TiO2 samples have been prepared at different dopant noble metal such as (Pd ,Pt, Ni, Ag,…) The main objective of this work are :
• 1. Characteristics of structural , microstructural and photoluminescence properties of thin films .
• 2. Studying the sensitivity and selectivity of these films doped with different noble metal deposited by PLD to CO gas.
6
Experimental Work
7
Prepared TiO2
Picture for TiO2 ceramic
Pulsed Laser Deposition (PLD)
Plasma plume
TiO2 thin film
Characterization Measurements of prepare films
Films thickness measurement
XRD Study
TCO film Morphology SEM ,AFM
Optical properties
photoluminescence properties
Gas sensor measurement
a)SEM b)AFM c)PL d)Gas sensing
c d
a ba b
Results
7
10
•Substrate Temperatures effect (Ts )
c
b
a
2θ (degree)
A :anatase
Figure (1) XRD spectra of TiO2/glass at different temperature a) 200ºC b) 300ºC, c)400ºC
Intensity (a.u)
laser fluence 0.8 J/cm2 oxygen pressure 5 *10-1 Torr
TiO2 /Si
FWHM and Main grain size
0
10
20
30
40
50
250 300 350 400 450 500 550
Temperature °C
Mai
n gr
ain
size
(nm
)
0.420.430.440.450.460.470.480.490.5
0.51
250 300 350 400 450 500 550
Temperature °C
FWH
M °
a b
Figure (3) TiO2 A(101) thin films grown on Si (111) at different substrate temperature for (a) main grain size (b)FWHM
Oxygen pressure effect
Fig (4) XRD patterns of TiO2 films grown on Siat various oxygen pressures a) 5×10-2 Torr b) 5×10-1 Torr c) 10 Torr
Intensity
(a.u)
2θ (degree)
Laser Fluence effect
Fig (5) XRD patterns of TiO2 films grown on Si
at various laser fluence a) 1.2 b) 0.8 c) 1.8 J/cm2
Doping effect of noble metal (Ag, Pt, Pd and Ni).
X - ray Florescence
Fig (7) X-ray florescence pattern for a) TiO2 pure b) TiO2 3% Ag c) TiO2 3% Pt d) TiO2 3% Pd e) TiO2 3% Ni .
a
b
SEM Substrate Temperatures effect (Ts )
Figure (8) SEM image of the TiO2/Si thin films deposited at various temperature of
a) 300°C, b) 400°C, c) 500°C, and laser fluence 1.2 J/cm2 ,O2 pressure=
10-1 mbar
Oxygen pressure effect
c
ba
Figure (9) SEM image of the TiO2/Si thin films deposited at various oxygen pressure a ) 5×10-2 mbar, b) 5×10-1 mbar and c) 10 mbar at
substrate temperature 500 °C and laser fluence 1.2 J/cm2
Doping effect of noble metal (Ag, Pt, Pd and Ni).
a
c
b
d
Figure (10) SEM image of the TiO2/Si thin films doping 3% with different noble metal a) Ag b) Pt c) Pd and d) Ni
SEM of plane grain size (nm) X-ray of plane grain size (nm) sample
29 31 TiO2 Pure 300°C
35 36.3 TiO2 Pure 400°C
40 41.28 TiO2 Pure 500°C
Table (1). The grain size of the TiO2 films
SEM of plane grain size (nm) X-ray of plane grain size (nm) O2 Pressure (mbar) sample
33 34 5×10-2 TiO2/Si
39 41 5×10-1 TiO2/Si
34 36 10 TiO2/Si
SEM of plane grain size (nm) X-ray of plane grain size (nm)
Dopants atom Radii (pm)
sample
15 15.7 126 TiO2 % 3 Ag
11 11.6 130 TiO2 % 3 Pt
20 21.5 72 TiO2 % Pd 3
18 19 69 TiO2 % Ni 3
Atomic Force Microscopy (AFM)
Substrate Temperatures effect (TS)
Figure (11) AFM image of the TiO2/Si thin films deposited at various substrate temperature ofa) 300°C, b) 400°C, c) 500°C, and laser fluence 1.2 J/cm2 ,O2 pressure=10-1 mbar
Oxygen Pressure effect
Figure (12) AFM image of the TiO2/Si thin
films deposited at various oxygen pressure a ) 5×10-2 mbar, b ) 5×10-1 mbar and c) 10
mbar at substrate temperature 500 °Cand laser fluence 1.2 J/cm2
doping effect of noble metal (Ag ,Pt ,Pd ,and Ni)
b
c
d
a
Figure (13) AFM image of the TiO2/Si thin films doping 3% with different noble metal
a) Ag b) Pt c) Pd and d) Ni substrate temperature 500 °C
and laser fluence 1.2 J/cm2 with O2
pressure=10-1 mbar.
Table (2). The RMS and roughness of TiO2 films from AFM
RMS roughness(nm) AFM of plane grain size (nm) X-ray of plane grain size(nm) sample
2.1 30 31 TiO2 Pure 300°C
4 34.4 36.3 TiO2 Pure 400°C11.2 42 41.28 TiO2 Pure 500°C
RMS roughness
AFM of plane grain size (nm) X-ray of plane grain size (nm) (O2) Pressure mbar sample
4 (nm) 32 34 5×10-2 TiO2/Si
6 nm 40 41 5×10-1 TiO2/Si
16.7nm 33 36 10 TiO2/Si
RMS roughness AFM of plane grain size (nm) X-ray of plane grain size (nm) sample
26 nm 16 15.7 TiO2 :3% Ag
28 nm 12.4 11.6 TiO2 :3% Pt
23 nm 23 21.5 TiO2 :3% Pd
24 nm 20.5 19 TiO2 :3% Ni
Optical Properties Transmission
0
10
20
30
40
50
60
70
80
90
100
0 200 400 600 800 1000
Wave length (nm)
T (%
)
TiO2 400 C
TiO2 300 C
TiO2 200 C
Substrate Temperatures effect (TS)
0
10
20
30
40
50
60
70
80
90
100
0 200 400 600 800 1000
Wave length (nm)
T
(%)
10 mbar
10 -2 mbar
10 -1 mbar
Oxygen Pressure effect
0
10
20
30
40
50
60
70
80
90
0 200 400 600 800 1000
Wave length (nm)
T (%
)
0.8 J/cm2
1.8 J/cm2
1.2 J/cm2
Laser Fluence effect
0
10
20
30
40
50
60
70
80
90
100
0 200 400 600 800 1000
Wave length (nm)
Tra
nsm
tan
ce %
TiO2 :3% Ag
TiO2 :3% Pd
TiO2 :3%Ni
TiO2 :3% Pt
TiO2 Pure
Doping effect of noble metal (Ag, Pt, Pd and Ni).
Optical Energy Gap Eg°
Substrate Temperatures effect (Ts )
doping effect of noble metal (Ag ,Pt ,Pd ,and Ni)
direct Eg
doping effect of noble metal (Ag ,Pt ,Pd ,and Ni)
Indirect Eg
Table (3) Physical and optical measurements for pure and doped TiO2 films
Optical energy gab E°g (eV)(indirect)
Optical energy gab E°g (eV)(direct)
Samples
3.03 3.4 TiO2 Pure at 200 °C
3.1 3.5 TiO2 Pure at 300 °C
3.2 3.6 TiO2 Pure at 400 °C
3.12 3.42 TiO2:1%Ag at 200 °C
3.20 3.5 TiO2 :2%Ag at 200 °C
3.28 3.67 TiO2 :3%Ag at 200 °C
3.11 3.41 TiO2 :1%Pt at 200 °C
3.19 3.52 TiO2 :2%Pt at 200 °C
3.25 3.58 TiO2 :3%Pt at 200 °C
2.93 3.42 TiO2:1%Pd at 200 °C
2.9 3.37 TiO2 :2%Pd at 200 °C
2.88 3.32 TiO2 :3%Pd at 200 °C
2.94 3.42 TiO2:1%Ni at 200 °C
2.9 3.38 TiO2 :2%Ni at 200 °C
2.8 3.35 TiO2 :3%Ni at 200 °C
Refractive index (n)
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
hv (eV)
Refra
ctiv
e in
dex
(n)
TiO2 400 C
TiO2 300 C
TiO2 200 C
Substrate Temperatures effect (TS)
doping effect of noble metal (Ag ,Pt ,Pd ,and Ni)
0
0.5
1
1.5
2
2.5
3
3.5
0 1 2 3 4 5
hv (eV)
Refr
acti
ve in
dex (
n) TiO2 Pure
TiO2 :1%Ag
TiO2 :2% Ag
TiO2 :3%Ag
0
0.5
1
1.5
2
2.5
3
3.5
0 1 2 3 4 5
hv (eV)
Refr
acti
ve in
dex (
n) TiO2 Pure
TiO2 :1% Pt
TiO2 :2% Pt
TiO2 :3%Pt
0
0.5
1
1.5
2
2.5
3
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
hv (eV)
Ref
ract
ive
inde
x (n
)
TiO2 Pure
TiO2 :3% Pd
TiO2 :2% Pd
TiO2 :1% Pd
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
hv (eV)
Ref
ract
ive
inde
x (n
)
TiO2 Pure
TiO2 :3% Ni
TiO2 :2%Ni
TiO2 :1% Ni
0
0.05
0.1
0.15
0.2
0.25
0.3
0 1 2 3 4 5
hv (eV)
extin
ctio
n co
effic
ient
(K)
TiO2 :3% Ag
TiO2 :2% Ag
TiO2 :1% Ag
TiO2 Pure
0
0.05
0.1
0.15
0.2
0.25
0.3
0 1 2 3 4 5
hv (eV)ex
tinct
ion
coef
ficie
nt (K
)
TiO2 :3%Pt
TiO2 :2%Pt
TiO2 :1%Pt
TiO2 pure
0
0.05
0.1
0.15
0.2
0.25
0.3
0 1 2 3 4 5
hv (eV)
extin
ctio
n co
effic
ient
(K)
TiO2 Pure
TiO2 :1%Pd
TiO2 :2%Pd
TiO2 :3%Pd
0
0.05
0.1
0.15
0.2
0.25
0.3
0 1 2 3 4 5
hv (eV)
extin
ctio
n co
effic
ient
(K)
TiO2 Pure
TiO2 :1%Ni
TiO2 :2%Ni
TiO2 :3%Ni
Extinction Coefficient
0
0.05
0.1
0.15
0.2
0.25
0.3
0 1 2 3 4 5
hv (eV)
exti
nct
ion
co
effi
cien
t (K
)
TiO2 200 C
TiO2 300 C
TiO2 400 C
Substrate Temperatures effect (TS)
doping effect of noble metal (Ag ,Pt ,Pd ,and Ni)
Photoluminescence (PL) Substrate Temperature effect (Ts)
c
a b
Figure (23) Photoluminescence spectrum of pure TiO2/glass thin films deposited at various substrate temperature of
a) 300°C, b) 350 °C, c) 400°C, and laser fluence 1.2 J/cm2 ,O2 pressure=10-1 mbar
The doping effect of noble metals (Ag ,Pt ,Pd ,and Ni)
a b
c d
Figure (24) Photoluminescence spectrum of the TiO2/glass thin films doping 3% with different noble metal a) Ag b) Pt c) Pd
and d) Ni ,at substrate temperature 400 °C
and laser fluence 1.2 J/cm2 with O2 pressure=10-1 mbar.
Table (4) Energy values and Intensity of PL Peaks
Samples Energy of PeakA (eV)
Intensity (a.u) Energy of Peak B (eV) Intensity (a.u) Optical energy gap (eV) E°
g
TiO2 at 300°C 3.06 840 2.39 365 3.03
TiO2 at 350°C 3.12 900 2.4 390 3.1
TiO2 at 400°C 3.22 1000 2.43 415 3.2
TiO2 :3% Ag at
400°C
3.24 280 2.45 150 3.28
TiO2 :3% Pt at
400°C
3.25 540 2.5 380 3.25
TiO2 :3% Pd at
400°C
2.93 810 2.33 350 2.88
TiO2 :3% Ni at
400°C
2.85 820 2.3 400 2.8
Sensing properties
Room Temperature
0
0.02
0.04
0.06
0.08
0.1
0.12
0 200 400 600 800 1000
Time (sec)
Sen
seti
vit
y
TiO2 Pure
TiO2:3%Pt
TiO2:3%Ag
TiO2:3%Pd
TiO2:3%Ni
Figure (24) Sensitivity for TiO2/glass pure and doping with a )Ag b)Pt c) Pd d) Ni as a function of operation time for CO gas at Room temperature and
laser fluence 1.2 J/cm2 with O2 pressure=10-1 mbar
Operation time Effect on sensing properties
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 100 200 300 400 500 600 700 800 900
Time (sec)
Sen
sit
ivit
y
TiO2 Pure
TiO2 :1% Ag
TiO2 :2% Ag
TiO2 :3% Ag
0
0.5
1
1.5
2
2.5
3
3.5
0 100 200 300 400 500 600 700 800 900
Time (sec)
Sen
sit
ivit
y
TiO2 Pure
TiO2 :1% Pt
TiO2 :2% Pt
TiO2 :3% Pt
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 100 200 300 400 500 600 700 800 900
Time (sec)
Sen
sit
ivit
y
TiO2 Pure
TiO2 :1% Pd
TiO2 :2% Pd
TiO2 :3% Pd
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 100 200 300 400 500 600 700 800 900
Time (sec)S
en
sit
ivit
y
TiO2 Pure
TiO2 :1% Ni
TiO2 :2%Ni
TiO2 :3% Ni
a b
dc
Figure (25) Sensitivity for TiO2/glass pure and doping with a )Ag b)Pt c) Pd d) Ni as a function of operation time for CO gas at operation temperature 250 °C and
laser fluence 1.2 J/cm2 with O2 pressure=10-1 mbar
Operation time Effect on resistance properties
0
2
4
6
8
10
12
0 200 400 600 800 1000
Time (sec)
Resis
tan
ce (oh
m)
*10
9
TiO2 Pure
TiO2 :1% Ag
TiO2 :2% Ag
TiO2 :3% Ag
0
2
4
6
8
10
12
0 200 400 600 800 1000
Time (sec)
Resis
tan
ce (oh
m)
*10
9
TiO2 Pure
TiO2 :1% Pt
TiO2 :2% Pt
TiO2 :3% Pt
0
2
4
6
8
10
12
0 200 400 600 800 1000
Time (sec)
Resis
tan
ce (oh
m)
*10
9
TiO2 Pure
TiO2 :1% Pd
TiO2 :2% Pd
TiO2 :3% Pd
0
2
4
6
8
10
12
0 200 400 600 800 1000
Time (sec)
Resis
tan
ce (o
hm
) *1
09
TiO2 Pure
TiO2 :1% Ni
TiO2 :2% Ni
TiO2 :3% Ni
Figure (26) resistance for TiO2/glass pure and doping with a )Ag b)Pt c) Pd d) Ni as a function of operation time for CO gas at operation
temperature 250 ° C and laser fluence 1.2 J/cm2 with O2 pressure=10-1 mbar
a b
c d
Operation time Effect on current properties
0
1
2
3
4
5
6
7
8
0 200 400 600 800 1000
Time (Sec)
cu
rren
t (n
A)
TiO2 pure
TiO2 1% Ag
TiO2 2% Ag
TiO2 3% Ag
0
1
2
3
4
5
6
7
8
9
10
0 200 400 600 800 1000
Time (Sec)
cu
rren
t (n
A)
TiO2 pure
TiO2 1%Pt
TiO2 2%Pt
TiO2 3%Pt
0
1
2
3
4
5
6
7
0 200 400 600 800 1000
Time (Sec)
cu
rren
t (n
A)
TiO2 pure
TiO2 1% Pd
TiO2 2% Pd
TiO2 3%Pd
0
1
2
3
4
5
6
0 200 400 600 800 1000
Time (Sec)
cu
rren
t (n
A)
TiO2 pure
TiO2 1% Ni
TiO2 2% Ni
TiO2 3% Ni
a
dc
b
Figure (27) current for TiO2 /glass pure and doping with a )Ag b)Pt c) Pd d) Ni as a function of operation time for CO gas at
operation temperature 250 ° C and laser fluence 1.2 J/cm2 with O2
pressure=10-1 mbar
Operation temperature Effect on sensing properties
0
0.5
1
1.5
2
2.5
3
0 50 100 150 200 250 300 350 400 450
T(C)
Sens
itivi
ty
TiO2 Pure
TiO2 :2% Ag
TiO2 :3% Ag
TiO2 :1% Ag
0
0.5
1
1.5
2
2.5
3
3.5
4
0 50 100 150 200 250 300 350 400 450
T(C)
Sens
itivi
ty
TiO2 Pure
TiO2 :2% Pt
TiO2 :3% Pt
TiO2 :1% Pt
0
0.5
1
1.5
2
2.5
0 50 100 150 200 250 300 350 400 450
T(C)
Sens
itivi
ty
TiO2 Pure
TiO2 :2% Pd
TiO2 :3% Pd
TiO2 :1% Pd
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 50 100 150 200 250 300 350 400 450
T(C)
Sens
itivi
ty
TiO2 Pure
TiO2 :2% Ni
TiO2 :3%Ni
TiO2 :1% Ni
Figure (28) Sensitivity for TiO2/glass pure and doping with 1% ,2% and 3% (Ag ,Pt ,Pd ,and Ni) films for CO gas at different operation temperature and laser fluence 1.2 J/cm2 with O2 pressure=10-1 mbar
a b
c d
Sensitivity of TiO2 /Si
0
5
10
15
20
25
0 100 200 300 400 500
T (C)
Sen
siti
vity
TiO2 Pure
TiO2:3% NI
TiO2:3% Pd
TiO2:3% Ag
TiO2:3%Pt
Figure (29) Sensitivity for TiO2/Si pure and doping with 3% (Ag ,Pt ,Pd ,and Ni) films for
CO gas at different operation temperature at laser fluence 1.2 J/cm2 with O2 pressure=10-1 mbar
Table (5) Sensitivity values of TiO2 pure and doping with different
noble metal concentration at operation temperature T= 250 °C.
Samples Sensitivity
TiO2 pure/glass 0.5
TiO2 :1% Ag /glass 1.7
TiO2 :2% Ag/glass 2.3
TiO2 :3% Ag/glass 2.7
TiO2 :1% Pt/glass 2.2
TiO2 :2% Pt/glass 3
TiO2 :3% Pt/glass 3.3
TiO2 :1% Pd/glass 1.5
TiO2 :2% Pd/glass 1.9
TiO2 :3% Pd/glass 2.2
TiO2 :1% Ni/glass 0.85
TiO2 :2% Ni/glass 1.2
TiO2 :3% Ni/glass 1.5
TiO2 pure/Si 7.5
TiO2 :3% Ag/ Si 17
TiO2 :3% Pt/ Si 23
TiO2 :3% Pd/ Si 15
TiO2 :3% Ni/ Si 12.5
The results in this work agreement with other results as shown in table below :
References Metal dopantTiO2Selectivity Sensitivity
[46] - CO 2
[136] - CO 4
[45] - Ethanol and methanol vapor 5
[30] Pt CO 20
[39] Pd CO , H24 , 2.5
[81] Nb CO 14
[this work] Pt CO 23
Ag CO 17
Pd CO 14
Ni CO 11
- CO 7.5
ConclusionPure TiO2 showed poor response to CO gas.3 % wt Ag ,Pt ,Pd and Ni doped TiO2 thin film was the
most sensitive element to CO gas .The optimum operating temperature for CO gas sensing was (250) °C . Ag ,Pt ,Pd and Ni doped TiO2 thin film would be
suitable for fabricating the CO gas sensors.The sensor TiO2 doping with Pt showed good
selectivity to CO gas. TiO2 deposited on silicon has sensitivity to CO gas
higher than TiO2 deposited on glass
Future Work• 1- Studying (TiO2) films as antireflection
coating on (p-n) junction solar cells and as a photocatalyst .
• 2- Using a mixing of background gas N2
+ O2 with high vacuum to enhancement the quality of the films.
• 3- Studying (TiO2) films as a gas sensor for NO2 and H2 gas .
•
Paper accepted
1- “Structural and optical properties of TiO 2 photocatalyst thin
film produced by PLD”.Iraqi Journal science 3rd Scientific conference Baghdad University. 2- "Investigation of structural and Morphology properties of Nanocrystalline thin films prepared by PLD ".Journal of the collage education in the 6th conference on physics .
Paper submitted 3-" Structure and Morphology properties of nanocrystalline noble metal doped films for gas sensing properties "-2nd conference of nano technology and advance material and their application .4-" Nanostructure dopants TiO2 films for gas sensing".
Iraqi Journal of applied physics .
UNIVERSITY OF TECHNOLOGY
Thank you