Effects of Gas Pressure on the Size Distribution and Structure of Carbon Nanoparticles Using Ar + CH₄Multi-Hollow Discharged Plasma Chemical Vapor Deposition

Abstract

Using an Ar + CH 4 multi-hollow discharge plasma chemical vapor deposition (MHDPCVD) method, carbon nanoparticles (CNPs) are synthesized in a size range between 10 nm and 100 nm at gas pressures from 2 Torr to 5 Torr. The size of the nanoparticles increases from 45.42 nm 3 at 2 Torr to 67.85 nm 3 at 5 Torr. The size dispersion also increases. Conversely, the optical emission intensities and generation of carbon related radicals decrease with increasing pressure. The Raman measurements indicate that these CNPs are composed of polymer structures containing relatively high clustered and distorted sp2 sites.

Time of Flight Size Control of Carbon Nanoparticles Using Ar+CH4 Multi-Hollow Discharge Plasma Chemical Vapor Deposition Method

“…Thus, d p was assumed to be equal to zero at t = 0, and the growth of CNPs stops at t = τ res . Figure 8 shows the dependence of d p on τ res , based on FR dependence, together with the results reported earlier [23]. Considering the larger size of CNPs for FR = 10 sccm, the size of CNPs linearly increases with increasing the τ res .…”

“…The surface-modified nanoparticles showed multi-exciton generation, which is necessary to increase solar cells' efficiency [18]. We recently used MHDPCVD to produce carbon nanoparticles [23][24][25] and confirmed that pressure played an important role in size control [23]. These studies revealed the essential parameters for the size control, while the growth mechanism was unclear.…”

“…Traditional plasma process has the discharge off period to wait for pumping out the particles from the gas phase, resulting in lower throughput. To date, we have successfully synthesized Si NPs and CNPs by using multi-hollow discharge plasma chemical vapor deposition (MHDPCVD), which can be produced continuously by employing fast gas flow [15][16][17][18][19][20][21][22][23]. In this method, the gas flow direction is uniform in the plasma region, and NPs are nucleated and grown in plasma.…”

“…NPs synthesis by the MHDPCVD method undergoes parametric tests such as dependence on gas pressure, gas flow rate, and gas composition, which are the external parameters [15][16][17][18][19][20][21][22][23][24]. Using the MHDPCVD, crystalline Si nanoparticles of 2 nm in size with 0.5 nm in size dispersion were produced for nanocrystalline amorphous silicon films for the third generation solar cells [15][16][17][18][19][20][21].…”

“…Hence, in this study, we measured the CNPs size dependence on the gas flow rate (FR) and discussed the growth mechanism of nanoparticles produced by the MHDPCVD method. Figure 1 illustrates a schematic diagram of the MHDPCVD reactor [23,24]. Powered and grounded electrodes have 8 holes of 5 mm diameter.…”