Comparative analysis of SnO
x
thin films deposited by reactive sputtering in different
SnO/Sn target compositions
Cheol Kim
1
, Yonghyun Won
1
, Sungdong Kim
2
, Sarah Eunkyung Kim
1
*
1
Graduate School of Nano-IT Design, Seoul National University of Science and Technology,
Korea
2
Department of Mechanical System Design Engineering, Seoul National University of Science
and Technology, Korea
*
Corresponding author
Tin oxide (SnO
x
) thin films have been widely investigated
because of outstanding
transmittance in visible range and excellent electrical conductivity. It has been well developed and
extensively used in many electronic and optoelectronic applications. Stable SnO
2
thin films generally
have n-type conductivity due to the existence of intrinsic defects such as oxygen deficiency and tin
interstitials, while meta-stable SnO thin films are commonly known as a p-type semiconductor. Also,
p-type characteristics can be achieved by doping in SnO
2
using elements with a lower valence cation as
the acceptor impurity in addition to tin monoxide (SnO).
Among various deposition techniques of SnO
x
thin films, rf reactive magnetron sputtering has been studied to deposit SnO
x
thin films in this study,
especially focusing on different compositions of SnO:Sn composite target. The most attractive point of
sputtering technique is a very convenient way to control the properties of thin films by changing various
process conditions and target material. Generally either
tin metallic target or tin oxide ceramic target are
used to produce
SnO
x
thin films.
The sputtering of a metallic target is very useful due to easy control of
various film properties and chemical compositions, while the sputtering of a ceramic target offers
structurally stable and better controllable stoichiometry. In this study, we have examined SnO:Sn
composite targets to obtain stable p-type
SnO
x
thin films, but to have some control of film defects for
electrical properties. We have evaluated 4 different composition ratios of SnO:Sn target: (1) 10:0 at%
(ceramic target), (2) 8:2 at% (composite target), (3) 5:5 at% (composite target), and (4) 0:10 at%
(metallic target).
SnO
x
thin films were deposited on a borosilicate glass substrate per various sputtering
conditions. The deposited thin films were studied by X-ray photoelectron spectroscopy and X-ray
diffraction for structural analysis, van der Pauw Hall effect measurement for electrical analysis, and
UV/VIS spectroscopy measurements for optical analysis.
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