Ta-doped SnO
2
polycrystalline films on glass using seed-layer technique by magnetron
sputtering
Rainald Mientus
1*
, Michael Weise
1
, Stefan Seeger
1
, Johanna Reck
1
, Klaus Ellmer
2
,
1
Optotransmitter-Umweltschutz-Technologie e.V., Köpenicker Str. 325, 12555 Berlin,
Germany
2
Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109
Berlin, Germany
* email:
Because of it’s potential of high mobility Ta-doped tin oxide (TTO) offers the possibility for
applications as transparent conductive electrodes in the VIS/NIR spectral region. Resistivities
as low as 1.1∙10
-4
Ωcm
and high mobilities up to 83 cm
2
/Vs
have been obtained by
PLD on TiO
2
seed layers with a transparency of about 85 % between (1-1.5) µm. Reactive
magnetron sputtering (MS) is a widely used technology for deposition of TCO especially due
to its independence of different vapour pressures of film components and scalability.
Resistivities as low as about 6∙10
-4
Ωcm and mobilities of about 26 cm
2
/Vs
for MS-
TTO on amorphous substrates have been reached. These authors usually used a deposition
temperature of about 500 to 800 °C, i.e., quite high for a glass deposition process.
Therefore, the aim of this work is proving the possibility of reactive magnetron sputtering
deposition of TTO on glass without intentionally heating combined with a subsequent
annealing step for preparing transparent conductive electrodes with higher NIR-transparency
than ITO.
The TTO films were prepared by reactive magnetron sputtering from a Sn(0,98)Ta(0,02)O
2
-
alloy target in an argon/oxygen gas mixture onto unheated glass substrates and seed-layer
coated substrates, respectively, and subsequently annealed.
Relationships between the deposition and annealing parameters of the TTO films and their
electrical characteristics (Hall and conductivity measurements) and optical properties
(UV/VIS and IR spectrometry) were investigated in detail. The stoichiometry is determined
by RBS and the crystallographic phase structure by X-ray diffraction (XRD).
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2
thin
films epitaxially grown on TiO
2
substrate. Applied Physics Letters 2008;93:132109.
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Exceeding 80 cm
2
V
-1
s
-1
in Polycrystalline Ta-Doped SnO
2
Thin Films on Glass
Using Anatase TiO 2 Seed Layers. Applied Physics Express 2010;3:031102.
[3] Weidner M, Jia J, Shigesato Y, Klein A. Comparative study of sputter-deposited SnO
2
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Sn
1- x
Ta
x
O
2
Films on Anatase-TiO
2
-Coated Glass. Japanese Journal of Applied
Physics 2010;49:108002.
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