1. 30 40 50 60
Intensity(a.u.)
2Theta degrees
P[Ar] = 0.21 Pa, FWHM = 0.268°, θpeak = 34.55°
P[Ar] = 0.43 Pa, FWHM = 0.299°, θpeak = 34.50°
P[Ar] = 0.65 Pa, FWHM = 0.339°, θpeak = 34.50°
P[Ar] = 0.83 Pa, FWHM = 0.344°, θpeak = 34.50°
(002)
(100)
(100)
Texturized Film
Charith I. Abeywarna1,2, Jaana S. Rajachidambaram1, Richard P. Oleksak1, and
Gregory S. Herman1, 2
1School of Chemical, Biological, and Environmental Engineering Oregon State University,
Corvallis, OR 97331
2Oregon Process Innovation Center for Sustainable Solar Cell Manufacturing
Microproducts Breakthrough Institute, Corvallis, OR 97330
Determining Sputter Condition
1E-02
1E-01
1E+00
2.4
2.5
2.6
2.7
2.8
4 5 6 7
Dep.Rate(nm/min)
Target - Substrate Distance (in)
Dep. Rate
Resistivity
Resistivity(Ω.cm)
1E-02
1E-01
1E+00
2.8
3
3.2
3.4
3.6
115 120 125 130 135 140
Dep.Rate(nm/min)
RF Power (W)
Dep. Rate
Resistivity
Resistivity(Ω.cm)
1E-02
1E-01
2
2.2
2.4
2.6
2.8
0.20 0.40 0.60 0.80
Dep.Rate(nm/min)
PAr (Pa)
Dep. Rate
Resistivity
Resistivity(Ω.cm)
P = 120 W
T-S = 5.2 in
P[Ar] = 0.21 Pa
T-S = 5.2 in
P[Ar] = 0.21 Pa
P = 120 W
Varying Pressure
Varying RF Power
Varying Target to Substrate Distance
Using the above data
analysis, we determined
that 5.2 inches for target
to substrate distance and
120 W for RF power was
optimal for growth of AZO
thin films due to the higher
deposition rates and lower
resistivities.
Optoelectric Properties
0
20
40
60
80
100
300 500 700 900 1100 1300 1500
Transmittance(%)
Wavelength (nm)
P[Ar] = 0.21 Pa
P[Ar] = 0.65 Pa
P[Ar] = 0.83 Pa
P[Ar] = 0.43 Pa
0
0.1
0.2
0.3
0.4
2 2.5 3 3.5 4
α2(105/cm2)
hν (eV)
P = 120 W, T-S = 5.2 in
EG (0.21 Pa) = 3.40 eV
EG (0.43 Pa) = 3.25 eV
EG (0.65 Pa) = 3.29 eV
EG (0.83 Pa) = 3.30 eV
Undoped ZnO Al doped ZnO
Overview
• Magnetron sputtering is widely used for
thin film depositions which can coat
virtually any surface over a wide range of
materials.
• Aluminum doped zinc oxide (AZO) is a
safe, low-cost, and abundant transparent
conductive oxide (TCO) used in various
applications for electronic devices, sensors
and photo-detectors.
• Deposition of AZO on Si/SiO2 substrate
was conducted by RF magnetron
sputtering at variable sputter conditions
including chamber pressure of Argon, RF
power, and target to substrate distance.
• A 3” diameter, ¼” thick, 98:2 wt.%
ZnO:Al2O3 target was used.
• Films were characterized by
• Film thickness – profilometry
• Resistivity – four-point-probe
• Crystallography – x-ray diffraction
• Optical properties – UV-Vis
• This study reports the optimization and
characterization of the deposited AZO film.
http://www.ecofriend.com/
http://www.vacengmat.com/photovoltaics_materials.html
http://arstechnica.com/science/news/2009
http://www.ecohttp://www.springerimages.com/Images/Chemistry
http://dtfl.snu.ac.kr/research2/ol/ZnO3.gif
Wurtzite - ZnO
Properties of deposited film were controlled
by varying PAr, RF power, and substrate to
target distance. Optimized sputter conditions
were determined to be 2.1 Pa, 120 W, and 5.2
inches, respectively. Films deposited at lower
Ar pressures were shown to be highly
oriented in the hexagonal c-axis (002). Thin
film AZO also shows high transmittance in
the visible range and a band gap of ~3.4 eV.
Conclusion
PAr
(Pa)
Dep. Rate
(nm/min)
Resistivity
(10-2 Ω.cm)
Band gap
(eV)
0.21 2.61 1.67 3.40
0.43 2.39 3.47 3.25
0.65 2.25 4.39 3.29
0.83 2.12 5.10 3.30
The shift in band gap
occurs as a result of
Burstein-Moss effect. This
is due to preferential
sputtering of oxygen from
the AZO film due to the
higher ion energy at lower
pressures.
http://arstechnica.com/science/news/2009
http://www.ipp.mpg.de/ippcms/de/
http://images-en.busytrade.com/
0.20
0.25
0.30
0.35
0.40
0
40
80
120
160
200
0.1 0.3 0.5 0.7 0.9
(002)FWHM
(002)PeakInt.(a.u.)
PAr (Pa)
(002) Peak Intensity
(002) FWHM