AVS 65th International Symposium & Exhibition
    Plasma Science and Technology Division Tuesday Sessions
       Session PS+EM+NS+SS-TuA

Paper PS+EM+NS+SS-TuA8
Synthesis of Hydrogenated Amorphous Carbon Nanoparticles using High-Pressure CH4+Ar Plasmas and Their Deposition

Tuesday, October 23, 2018, 4:40 pm, Room 104A

Session: Plasma Processing of Challenging Materials - II
Presenter: Kazunori Koga, Kyushu University, Japan
Authors: K. Koga, Kyushu University, Japan
S.H. Hwang, Kyushu University, Japan
K. Kamataki, Kyushu University, Japan
N. Itagaki, Kyushu University, Japan
T. Nakatani, Okayama University of Science, Japan
M. Shiratani, Kyushu University, Japan
Correspondent: Click to Email
Nanostructure fabrication such as nanoparticles through bottom-up processes is important in nanotechnologies due to their size-related properties [1]. Plasma is a powerful tool to produce nanoparticles. To control their size, pulsed discharge plasmas are commonly employed, but the plasmas have the limitation of the throughput. To realize continuous production, we have developed a multi-hollow discharge plasma chemical vapor deposition (MHDPCVD) method. We have succeeded in producing crystalline Si nanoparticles of 2 nm in size using hydrogen diluted silane plasmas [2, 3]. Here we applied the method to synthesis carbon nanoparticles. The experiments are carried out by CH4+Ar MHDPCVD. CH4 and Ar were injected into the reactor, flowed through hollows of 5 mm in diameter in the electrode. The gas flow rate ratio of CH4 and Ar was 1:6. The total gas flow rate was 10 to 200 sccm . The pressure was kept at 2 Torr. Discharges were generated in hollows by applying rf power of 40 W at 13.56 MHz. Nanoparticles are nucleated and grow in the discharges. They are transported outside of the discharges by the fast gas flow and the growth of the nanoparticles are stopped. They deposited on TEM mesh grids set on the substrate holder 50 mm far from the electrode. From TEM measurements, spherical nanoparticles were deposited on the grid. The mean size decreases from 270 nm for 10 sccm to 20 nm for 120 sccm . The gas residence time for 120 sccm is 1/12 of that for 10 sccm . The size for 120 sccm is 1/13.5 of that for 10 sccm . The results indicate that the size of carbon nanoparticles are controlled by gas residence time of nanoparticles in plasmas. Above 125 sccm, No nanoparticle is observed on the TEM mesh. It suggests that deposition of nanoparticles depends on gas flow velocity and direction on the substrate.

[1] M. Shiratani, et al., J. Phys. D 44 (2011) 174038.

[2] T. Kakeya, et al., Thin Solid Films 506 (2006) 288.

[3] K. Koga et al., ECS Transactions 77 (2017) 17.