Synthesis of Carbon Nano Tubes on Silicon Substrates Using Alcohol Catalytic Chemical Vapor Deposition

Abstract

The technique used for synthesizing large quantity carbon nanotubes (CNTs) directly on the surface of silicon substrates has been developed by means of the alcohol catalyst chemical vapor deposition ACCVD method using ethanol. The proposed method adopts an easy and costless liquid-based dip-coat approach for mounting the catalytic metals on the substrates. Reasonable quality formation of catalyst preparation was found at 5 min of dipping the substrate into cobalt acetate solution and withdrawing at speed of 4 cm/min followed by heat treatment at 400°C. Cobalt acetate catalyst on silicon substrates were analyzed using an atomic force microscopy (AFM) and scanning electron microscopy (SEM). The substrate surface is blackened with a layer of CNTs after the ACCVD at an optimum condition. The grown CNTs were analyzed using transmission electron microscopy TEM, SEM, XRD, UV/Vis-NIR spectroscopy and photoacoustic (PA) measurements of thermal parameters. Large quantities of single and multi walled carbon nanotubes were grown at a growth time of 50 min and growth temperatures of 800 and 900°C. UV-Vis/NIR spectroscopy detected two absorption peaks at 0.78 and 1.35 eV and optical energy gap (E_opt) of 1.16 eV for CNTs grown at 800°C. The PA measurements of thermal parameters detected maximum values of thermal diffusivity, effusivity and conductivity for those grown at 800°C.