Contribution of radicals and ions in catalyzed growth of single-walled carbon nanotubes from low-temperature plasmas

Abstract

K. (2015). Contribution of radicals and ions in catalyzed growth of single-walled carbon nanotubes from low-temperature plasmas. Physics of Plasmas, 22 013504-1-013504-10. Contribution of radicals and ions in catalyzed growth of single-walled carbon nanotubes from low-temperature plasmas AbstractThe growth kinetics of single-walled carbon nanotubes (SWCNTs) in a low-temperature, low-pressure reactive plasma is investigated using a multiscale numerical simulation, including the plasma sheath and surface diffusion modules. The plasma-related effects on the characteristics of SWCNT growth are studied. It is found that in the presence of reactive radicals in addition to energetic ions inside the plasma sheath area, the effective carbon flux, and the growth rate of SWCNT increase. It is shown that the concentration of atomic hydrogen and hydrocarbon radicals in the plasma plays an important role in the SWCNT growth. The effect of the effective carbon flux on the SWCNT growth rate is quantified. The dependence of the growth parameters on the substrate temperature is also investigated. The effects of the plasma sheath parameters on the growth parameters are different in low-and high-substrate temperature regimes. The optimum substrate temperature and applied DC bias are estimated to maximize the growth rate of the single-walled carbon nanotubes. Contribution of radicals and ions in catalyzed growth of single-walled carbon nanotubes from low-temperature plasmas The growth kinetics of single-walled carbon nanotubes (SWCNTs) in a low-temperature, low-pressure reactive plasma is investigated using a multiscale numerical simulation, including the plasma sheath and surface diffusion modules. The plasma-related effects on the characteristics of SWCNT growth are studied. It is found that in the presence of reactive radicals in addition to energetic ions inside the plasma sheath area, the effective carbon flux, and the growth rate of SWCNT increase. It is shown that the concentration of atomic hydrogen and hydrocarbon radicals in the plasma plays an important role in the SWCNT growth. The effect of the effective carbon flux on the SWCNT growth rate is quantified. The dependence of the growth parameters on the substrate temperature is also investigated. The effects of the plasma sheath parameters on the growth parameters are different in low-and high-substrate temperature regimes. The optimum substrate temperature and applied DC bias are estimated to maximize the growth rate of the single-walled carbon nanotubes.

Investigations on the effect of process parameters on the growth of vertically oriented graphene sheet in plasma‐enhanced chemical vapour deposition system

“…The outcomes of the computations are linked to the input parameters for the surface deposition model to study the growth characteristics of VOGS over the catalyst (copper) nanoislands placed over the silicon substrate surface. The catalyst nanoislands have peculiar ability to dissociate the hydrocarbon and hydrogen species on their active surface to generate building units (carbon species) of the graphene sheet and hydrogen radicals, which etch and sharpen the edges TA B L E 5 Descriptions of all the functional terms used in the Equation (2) and their corresponding reactions involved [35][36][37][38][39]…”

“…The numerical data obtained from the computational model are linked as the input parameters for the surface deposition model that accounts the dissociation of hydrocarbon species on the catalyst nanoislands surface via various inherent complex processes, generation of carbon clusters, formation of graphene nuclei, and lateral growth of graphene, which eventually turn into the vertical growth as discussed in Section 2. The outcomes of the computational model and analytical results of the TA B L E 4 Descriptions of all the functional terms used in the Equation (1) and their corresponding reactions involved [35][36][37][38][39] Term Reaction involved Description…”

Modelling the effects of nitrogen doping on the carbon nanofiber growth via catalytic plasma‐enhanced chemical vapour deposition process

“…D m [=D m0 exp(− SD /k B T s )] is the metal atoms' diffusion coefficient, [31] and E th (=1.87 eV) is the energy for thermal dehydrogenation of hydrocarbons. [33] All complex processes involved in Equation 13 to describe the growth mechanism of N-CNFs on the catalyst nanoparticle are listed in Table 4. The surface and bulk diffusion of carbon species significantly affect the growth of nanostructures, and their relative contribution depends on the catalyst nanoparticle temperature.…”

“…is the ions flux on the catalyst nanoparticle surface from the plasma, [32] is the thermal vibration frequency, ads (= 6.8 × 10 −16 cm 2 ) is the cross section for the interaction among the various species, [32] E td (= 2.1 eV) is the hydrocarbons dissociation energy, E ev (= 1.8 eV) is the carbon evaporation energy, and E dhc (=1.8 eV) is the hydrocarbon desorption energy. [33] The explanation of various terms as well as their corresponding surface reactions involved in the Equation 12 are listed in Table 3.…”

Plasma-deposited hydrogenated amorphous silicon films: multiscale modelling reveals key processes

“…These results are in good agreement with the relevant experimental results. 40,41 The hydrogen abstraction increases with the surface temperature T s , this in turn leads to the increase of dangling bond density and growth rate of the lm. Fig.…”