Characteristics of Fe–Si Thin-Film Catalysts and Their Effects on the Growth of Carbon Nanotubes

Abstract

Aligned carbon nanotubes were obtained at 370°C in a microwave plasma-enhanced chemical vapor deposition system using hydrogen-etched Fe-Si thin films as the catalyst. Effects of the catalyst characteristics on the growth of carbon nanotubes ͑CNTs͒ have been investigated. The surface of a hydrogen-etched Fe-Si thin-film catalyst consists of particles having a core-shell structure. There may also be an amorphous smooth layer beneath the particle layer. Although it is often reported that the growth and the diameter of CNTs correlate to the size of the particles on the surface of an etched catalyst film, we found that it is the smooth layer but not the particles that is critical to the CNT growth. Depending on the characteristics of the smooth layer, different amounts of CNTs were obtained at different growth rates. Optimal characteristics of the smooth layer were determined.

Growth of Carbon Nanotubes on Metallic Substrates Using a Substrate-Shielded Microwave Plasma-Enhanced Chemical Vapor Deposition

“…This is in accordance with previous studies. 16,17,43 The microstructure was further examined using Raman spectroscopy. Fig.…”

“…1 Due to their unique properties, CNTs have been found to useful in many applications, for example, electrochemistry. [2][3][4][5][6][7] Methods including chemical vapor deposition (CVD), [8][9][10][11] plasma-enhanced CVD (PECVD), 12 microwave plasma-enhanced CVD (MPECVD) [13][14][15][16][17][18][19][20][21][22] are widely used for the synthesis of CNTs. The substrates used are either non-metallic or metallic.…”

“…37,38 In summary, regardless the use of plasma or not, CNT growth rates on metallic substrates are much lower than that on non-metallic substrates. [13][14][15][16][17][18][19][20][21] z E-mail: jting@mail.ncku.edu.tw…”