講演番号をこちらに

05aE20P
表面波プラズマCVD法によるカーボンナノ材料の低温合成に関する質量分析研究

Mass Spectrometric Study on the Low-temperature Synthesis of Carbon
Nanomaterials by Surface-wave Plasma CVD
ラマン ベカレビッチ 1, アレクサンダー ロガチョウ 2, 永津 雅章 1
Raman Bekarevich1, Aleksandr Rogachev2, Masaaki Nagatsu1
1.

静大創造科技院、 2. ゴメル州立大
1.
Shizuoka University, Hamamatsu, Japan;
2.
Francysk Skaryna Homiel State University, Homiel, Belaruś
Electronic devices currently hold an important
place in human life. During the past two decades
scientists all over the world make a lot of efforts tofabricate electronic devices based on the carbon
nanotubes (CNTs). Significant progress have been
made in this field: direct synthesis of CNTs fromcontrolled locations on surfaces of the substrate,
direct synthesis on different substrates including
metal electrodes also has been achieved [1]. These
accomplishments
helpedimplement
many
applications like CNT-based field-effect transistors,sensors and others. However, despite this progress,
high temperature of the CNTs synthesis limits thenumber of potential applications of CNTs. A lot ofefforts have been made to reduce the temperature ofgrowth in order to make the nanotube fabricationcompatible with more substrates and applications.
Different ways to reduce temperature have been
proposed, but one of the most promising methods torealize low-temperature synthesis of carbon
nanomaterials (CNMs) is the plasma-enhanced
chemical vapor deposition.
Recently we demonstrated successful synthesisof CNTs onto polyimide substrate bymicrowave-exited surface-wave plasma CVD atrelatively low-temperature of 250°C using
double-step treatment: NH3 plasma pre- treatment
and CNMs growth in NH3/CH4 plasma [2].
However few-layered graphene sheets have been
observed together with multiwalled CNTs, what canbe problem in case of real application of obtainedmaterial. To solve a problem of controllable growthof each type of CNMs it is necessary to understandmechanism of CNMs growth. To do it, in this study,
we carried out the investigation of positive ionscontaining in the plasma used during thepretreatment as well as CNMs growth.
The results of NH3 plasma investigation arepresented in Fig. 1. It is seen that mass spectrum of
the studied plasma consist of several peaks
corresponding to different types of positive ions.
Various ions have a different effect on the treatedsample, i.e. hydrogen ions are responsible to theetching of amorphous carbon from the substrate
while the nitrogen containing ions may lead to thesurface modification of sample. Thus, it is very
important to find correct ratio of the ions peaks to
be able to get high quality CNMs. Inset of Fig. 1
demonstrates dependence of NH3+/H3+ andNH3+/H3+ ions intensities on the microwave input
power. When this ratio is high, etching effect ofammonia plasma is not very strong, because
relative concentration of hydrogen ions is rather low,and oppositely, low NH3+ /Hx+ ratio means existenceof large amount of hydrogen ions in plasma andtherefore we can expect that plasma at these
conditions have strong etching effect. The details of
this experimental work will be presented at theconference.
NH3+
H3+H+NH4+

N2+Fig. 1 Mass spectrum of positive ions in NH3
plasma. Inset: efect of the input microwave power
on ions peaks intensity ratio.
References[1] M. Hofmann, S. Bhaviripudi, J. Kong, in: J.
Kong, A. Javey (Eds.), Carbon Nanotub. Electron.,
2009: pp. 43–61.
[2] R. V. Bekarevich, S. Miura, A. Ogino, A. V.
Rogachev, M. Nagatsu, J. Photopolym. Sci.
Technol. 25 (2012) 545–549.