22nd International Symposium on Plasma Chemistry
July 5-10, 2015; Antwerp, Belgium
Plasma-assisted growth of indium oxide nanostructures
P.Y. Lin1, Y.C. Wang1, T.M. Kuan2, C.W. Kuo2, C.Y. Yu2 and I.C. Chen1
1
Institute of Materials Science and Engineering, National Central University, Zhongli 320, Taiwan
2
TSEC Corporation, Hsinchu 303, Taiwan
Abstract: Plasma-assisted growth of indium oxide nanostructures was performed in
electron cyclotron resonance (ECR) plasma via the vapor-liquid-solid mechanism. The
morphology of the indium oxide nanostructures is strongly dependent on the input
precursor flow rate. Effective growth of indium oxide nanowires at temperatures as low as
220 °C has been achieved.
Keywords: plasma-assisted growth, indium oxide, chemical vapor deposition
1. Introduction
Indium oxide (In 2 O 3 ) which is an exceeding wide band
gap (3.6 eV) oxide material has attracted a great deal of
interest because of its unique properties of high
transparency and simultaneously metallic conductivity [1].
In 2 O 3 nanostructures have potential applications not only
in optoelectronic and electronic devices, but also as fieldeffect transistors, chemical sensors and bio-sensing
devices. There are considerable studies on the synthesis
and properties of In 2 O 3 nanostructures with various
morphologies. Most research works focus on the
preparation and properties of In 2 O 3 films or
nanoparticles. Recently, In 2 O 3 nanostructures have been
synthesized using various methods such as thermal
evaporation, pulsed laser deposition and reactive
magnetic sputtering [2, 3].
The development of integration of semi-conductor
nanostructures on flexible or low-cost substrates (e.g.,
polymer foils) has been extensively researched in recent
years. With relatively low decomposition temperatures,
most polymers cannot survive the growth temperature
used in most of the VLS processes. As a result, there is
great interest in the low-temperature growth of
semiconductor nanostructures. To realize the low
temperature process, application of plasma in chemical
reactions has attracted considerable research attention
owning to its high dissociation of incoming gas and local
heating on the surface of the metallic particles [4, 5].
In this study, low temperature, plasma-assisted growth
of In 2 O 3 nanostructures was carried out in an electron
cyclotron resonance (ECR) plasma with using indium
nanocrystals as seed particles via the vapor–liquid–solid
mechanism. The flow ratio of precursor gases was found
to be a key factor for control of morphology of In 2 O 3
nanostructures. A systematic study of the flow-ratio
dependence of the nanorod growth rate is presented.
2. Experimental procedures and results
First, the indium catalyst was deposited on the glass
substrate by an electron-beam evaporator.
The indium-coated glass was then placed into the ECR
chemical vapor deposition (ECRCVD) system and heated
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up to 220 °C for In 2 O 3 growth using a feed gas mixture
of Ar and O 2 . During the deposition, the applied
microwave power and working pressure were kept at 700
W and 20 mTorr, respectively. The actual substrate
temperature was measured using a temperature label in
contact with the sample surface. For the characterization,
the microstructure and morphology of as-grown Ge-NWs
were investigated by transmission electron microscopy
(TEM) and scanning electron microscopy (SEM). High
resolution x-ray diffraction (HRXRD) was used to
examine the crystal structures of the samples.
Fig. 1 shows the SEM images of In 2 O 3 nanostructures
grown from indium nanoparticles with various Ar and O 2
flow ratios during growth. As can be observed, the
morphology of Ge nanostructures is strongly dependent
by the flow ratio.
Fig. 1 SEM images of In 2 O 3 nanostructures grown using
various Ar/O 2 flow ratios of (a) 200/1, (b) 80/1, (c) 40/1
and (d) 20/1.
3. Acknowledgments
This research was supported by the National Science
Council of Taiwan under grant nos. 103-2221-E-008-041
and 103-2622-E-008-012 -CC3.
1
4. References
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