Magnetron-type radio-frequency plasma control yielding vertically well-aligned carbon nanotube growth

Abstract

In order to understand the effects of plasma parameters on the nanotube formation and further controlled growth, we have investigated the optimal growth condition using a rf plasma-enhanced chemical vapor deposition method. The magnetic field introduced for a magnetron discharge enhances the nanotube growth as a result of the plasma-density increment and the self-bias reduction of a rf electrode. It is also found that the optimum ion flux and ion bombardment energy is a key parameter for the uniform, well-aligned, and density-controlled nanotube growth.

Recent Progress of Plasma CVD for Structure Controlled Growth of Single-Walled Carbon Nanotubes

“…The total pressure was kept at 50 Pa by adjusting the pumping rate of the rotary pump throughout this experiment. Lower H 2 concentrations (0 and 3 sccm) led to larger diameters and wider (n,m) distributions with (6,5), (7,5), (7,6), (8,4), (8,6), and (8,7) (Figures 6a and b). On the other hand, the 7-sccm H 2 concentration yielded the narrowest (n,m) distribution with a dominant peak corresponding to the (6,5) tube (Figure 6c).…”

“…Figures 8a-c show the PLE maps of the as-grown SWNTs as a function of t g . It is found that the d t distribution just after the incubation (2 sec) is relatively narrow and the main diameter is about 0.8 nm with (6,5), (7,5), (7,6), (8,4), and (9, 2) dominant chiralities (Figure 8a). Then, the relatively large d t (0.95 nm) SWNTs ((8, 6) and (9, 4)) initiate their growth at 5 sec (Figure 8b).…”

“…Then, the relatively large d t (0.95 nm) SWNTs ((8, 6) and (9, 4)) initiate their growth at 5 sec (Figure 8b). The larger d t SWNTs of (8,7) are finally grown at 10 sec, where the chirality and d t distributions are broad (Figure 8c). The small end of the d t does not change, whereas the large end increases with an increase in the t g .…”

“…Figure 10 shows the PLE map dependence on the growth temperature of SWNTs grown for the very short growth time (2 sec). Interestingly, when we decrease the growth temperature down to 600 ºC the chirality distribution is very narrowed, and (7,6) and (8,4) SWNTs are predominantly grown (Figure 10c). At the lower growth temperature (≤ 580 ºC), SWNTs could not be grown for the very short growth time (2 sec).…”

“…In general, CVD can be divided into two types: thermal CVD [1][2][3][4] and plasma CVD [5][6][7]. Due to the strong electric fields in plasma sheaths, nanotubes grown by plasma CVD tend to have an individually-and vertically-freestanding shape [5,[8][9][10]. Thermal CVD decomposes carbon source gases using thermal energy.…”