Transcript Document

Soňa Flickyngerová1), Marie Netrvalová2), Lucie Prušáková2),
2)
1)
1)
Veronika Vavruňková , Andrea Pullmannová , Erik Vavrinský ,
Pavel Gašpierik1), Peter Ballo1), Ivan Novotný1),
2)
1)
Pavel Šutta , Vladimír Tvarožek
Dep. of Microelectronics, Faculty of Electrical Engineering & Information Technology Slovak University of Technology, Ilkovičova 3, SK-812 19, Bratislava, Slovakia
2 2Department New Technologies Research Center, The University of West Bohemia, Univerzitní 8, 306 14 Plzeň, Czech Republic
1
Technology & Results
Aim
300000
Ts = RT
150000
900 W
100000
1500
100°C
1000
300°C
RT
500
0
32
33
34
35
36
0
32
37
96
88
84
Ts = RT
80
600
700
Power [W]
800
36
37
RF = 800W
92
88
84
80
900
33
34
35
2 (degrees)
36
37
Ts = RT
RF= 800W
92
88
84
80
76
0
1600
100
200
Substrate temperature [°C]
0
300
100
200
300
400
Annealing temperature [°C]
160
Ts = RT
RF= 800W
60
120
800
100
Rs []
1000
Rs []
Rs []
RF = 800W
140
Ts = RT
80
600
400
60
200
40
0
20
500
600
700
800
900
40
20
0
Power [W]
Ta = 400°C
100
200
Substrate temperature [°C]
0
300
100
200
300
400
Annealing temperature [°C]
8
8
7
7
7
6
5
Ts = RT
4
3
2
1
500
600
700
Power [W]
800
900
6
Figure of merit [%/]
8
Figure of merit [%/]
Figure of merit [%/]
Figure of merit F=T/RS
0
Special thanks to Dr. I. Vavra for TEM analyses
35
Sheet resistance
1200
Cross-sectional
TEM of AZO thin
film reveals the
columnar structure
in [001] direction
perpendicular
to
surface
34
76
1400
Plan view TEM
micrograph of AZO
thin films sputtered
at 800 W. The mean
grain size is approx.
50 nm
33
0
32
Transmittance [%]
Transmittance [%]
92
RF = 800 W
Rq = 8 nm
400°C
100000
96
TS = RT
Ra = 6 nm
300°C
96
After deposition
Post-deposition annealing in
80% N2 + 20% H2
150000
Optical transparency l = 400 - 1000 nm
500
Rq = 14 nm
200000
2  (degrees)
2 (degrees)
Ts = RT
RF= 800W
200°C
50000
700 W
76
Ra = 11 nm
250000
RF = 800W
2000
600 W
500 W
50000
200°C
Intensity (counts)
800 W
200000
RT
2500
Intensity (counts)
250000
Post-deposition annealing
temperature Ta = 200 – 400°C
in 80% N2 + 20% H2
3000
300000
Transmittance [%]
Aluminum
atom
migrates from initial
position along dashed
black arrow to the
stable position where
is situated between
the
two
Oxygen
atoms. The atom in
the stable position is
shown in blue.
Substrate temperature
Ts =RT - 300°C during deposition
Crystalline structure
RF power
500 – 900 W
Intensity (counts)
A study of the effect of technology parameters
- sputtering power, substrate temperature and
post-deposition annealing –
on structural, electrical and optical properties of
aluminium-doped zinc oxide (AZO) thin films
was carried out.
LDA electron density calculated for ZnO doped
by Aluminum. The Figure shows a
cut in the plane (010) of 32 atom supercel. The
purple
spheres
are
Zinc
atoms
and the dark red spheres are Oxygen atoms.
RF= 800W
5
4
3
6
5
4
3
2
2
1
1
0
100
200
Substrate temperature [°C]
300
Ts = RT
RF= 800W
0
100
200
300
400
Annealing temperature [°C]
Conclusion
 Use of Al doped ZnO (substitution Zn by Al in the lattice) can increase of electron concentration i.e.
higher conductivity.
 From XRD analyses, the 2Θ shifts up with increasing RF powers and both substrate/annealing
temperatures as a result of the increase of Al3+ substituents and a reduction of the lattice parameter,
which changes the lattice distortion in AZO films from compressive to tensile lattice stresses.
 Desired properties of AZO thin films for solar cell application:
the high figure of merit F = T/ Rs ≥ 4 %/Ω, low sheet resistance Rs ≤ 10 /square and the transmittance
T ≥ 82%, including the glass substrate - were obtained in highly oriented (002) AZO films prepared at
RF power of 800 W, substrate temperature of 200ºC and annealing in the forming gas at 400ºC.