Tuning vertical alignment and field emission properties of multi-walled carbon nanotube bundles

• Published in: Applied physics. A, Materials science & processing Materials science & processing, 2018, Vol.124 (1), p.1-9, Article 52
• Main Authors: Sreekanth, M., Ghosh, S., Srivastava, P.
• Format: Article
• Language: English
• Subjects: Alignment; Applied physics; Bundles; Carbon; Catalysis; Characterization and Evaluation of Materials; Chemical vapor deposition; Condensed Matter Physics; Current density; Entanglement; Field emission; Machines; Manufacturing; Materials science; Multi wall carbon nanotubes; Nanotechnology; Nanotubes; Optical and Electronic Materials; Physics; Physics and Astronomy; Processes; Self-assembly; Silicon substrates; Structural analysis; Surfaces and Interfaces; Thin Films; Xylene
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-017-1471-7

We report the growth of vertically aligned carbon nanotube bundles on Si substrate by thermal chemical vapor deposition technique. Vertical alignment was achieved without any carrier gas or lithography-assisted deposition. Growth has been carried out at 850 °C for different quantities of solution of xylene and ferrocene ranging from 2.25 to 3.00 ml in steps of 0.25 ml at a fixed concentration of 0.02 gm (ferrocene) per ml. To understand the growth mechanism, deposition was carried out for different concentrations of the solution by changing only the ferrocene quantity, ranging from 0.01 to 0.03 gm/ml. A tunable vertical alignment of multi-walled carbon nanotubes (CNTs) has been achieved by this process and examined by scanning and transmission electron microscopic techniques. Micro-crystalline structural analysis has been done using Raman spectroscopy. A systematic variation in field emission (FE) current density has been observed. The highest FE current density is seen for the film grown with 0.02 gm/ml concentration, which is attributed to the better alignment of CNTs, less structural disorder and less entanglement of CNTs on the surface. The alignment of CNTs has been qualitatively understood on the basis of self-assembled catalytic particles.