Synthesis of carbon nanotubes on nickel catalyst by low pressure chemical vapour deposition

Abstract

Carbon nanotubes (CNTs) are synthesized using Low Pressure Chemical Vapour Deposition (LPCVD) at 750 °C with a Nickel (Ni) catalyst, and have been explored as electron field emission electrodes. Initially, an N-type cleaned Si substrate is coated with Nickel catalyst via RF sputtering. This catalyst-deposited Si substrate is then heated to 750 °C to form nano-islands of catalyst within the LPCVD chamber. Vector gases, Ammonia and Hydrogen, with a flow rate of 170 sccm, are allowed to pass through the tube reactor for 25 minutes. Acetylene, serving as a source gas with a flow rate of 40 sccm, is introduced for 15 minutes at 750 °C. The surface morphology of the as-grown CNTs is characterized using a Scanning Electron Microscope (SEM). The images reveal successful growth of CNTs, with diameters ranging from 25 to 55 nm and lengths extending to several micrometers. LPCVD is a widely used method for CNT production, especially for mass production. Our results demonstrate high density and aligned growth of CNTs, possibly attributed to Ni being easily impregnated on a Si substrate, which is crucial for achieving good adhesion between the catalyst and Si substrate.