Apparatusdevelopment for Diamond Synthesis from Acetone Vapor with Low Energy Consumpution
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APPARATUSDEVELOPMENT FOR DIAMOND SYNTHESIS FROM ACETONE VAPOR WITH LOW ENERGY CONSUMPUTION Fumitomo Onishi, Rie Hayashi, Yoshiki Takagi Teikyo Univ. of Science & Technology, 2525 Yatsusawa, Uenohara-machi, Kitatsuru-gun, Yamanashi-Pref.,409-0193,JAPAN. ABSTRACT
We synthesized diamond via gaseous phase of vaporized acetone. Molecular acetone decomposes to two methyl radicals with thermal activation. We propose here a new method for diamond synthesis with these methyl radicals from molecular acetone. With this method, we successfully synthesized diamond particles with shorter experimental time than conventional method. With liquid carbon source, such as acetone, impurity elements will be easily substituted in synthesized diamond thin, film which has wide applications for the future electronic devices. INTRODUCTION
K.Fabisiak et al. reported diamond synthesis on various substrates [1]. They used thermal filament method with acetone and hydrogen mixture gas flow system. Okoshi et al. synthesized diamond-like carbon from laser abrasion with frozen acetone[2]. One acetone molecule has two methyl groups, which has very important role on diamond synthesis with gaseous reactions. Acetone molecule reacts with hydrogen molecules and produces two methane molecules and one carbon mono-oxide. Liquid carbon sources including acetone are listed on Table 1. One molecule of these five liquid carbon sources has 2, 1, 2, 2, and 4 methyl groups, which are reported as significant role on diamond synthesis. So it is expected that diamond synthesis with relatively low activation energy consumption. EXPERIMENTAL Tungsten filament was set to perpendicular to substrate on the center of the reaction
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chamber. After air was evacuated, liquid carbon source was introduced on the chamber and vaporized to 1 Torr with room temperature, and then hydrogen gas was introduced with 51 Torr in total pressure. After all valves were closed, diamond synthesis was started with filament heated up. Table.1 Liquid carbon sources and their Molecular formula with Molecular weight Molecular formula
Molecular weight g/mol
Acetone
(CH3)2CO
58.078
Methanol
CH3OH
32.042
Ethanol
CH3CH2OH
46.068
Ethylene glycol
HOCH2CH2OH
62.068
Tertiary butyl alcohol
(CH3)3COH
74.122
Temperature of filament was 2200 deg centigrade, substrate temperature was 780 deg C, synthesizing time was 60 minutes, distance between substrate and filament was 2.5 mm, electric power was 200W. Substrates were Silicon single crystal with p-type (100) with 10 x 300 mm in size. Figure 1 shows the schematic figure of reaction chamber. Tungsten filament
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RESULTS AND DISCUSSION Figure 2 shows SEM photograph of particles synthesized from acetone vapor. And figure 3 shows SEM photo of particles synthesized from methanol.
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Figure 2 Particles synthesized from acetone Figure 3 Particles synthesized from methanol Figure 4 shows SEM photograph of particles synthesized from ethanol. And figure 5 sh
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