Synthesis of vertically aligned thin multi-walled carbon nanotubes on silicon substrates using catalytic chemical vapor deposition and their field emission properties

Abstract

We have succeeded in synthesizing vertically aligned thin multi-walled carbon nanotubes (VA thin-MWCNTs) by a catalytic chemical vapor deposition (CCVD) method onto Fe/Al thin film deposited on a Si wafers using an optimum amount of hydrogen sulfide (H 2 S) additive. Scanning electron microscope (SEM) images revealed that the as-synthesized CNT arrays were vertically well-oriented perpendicular to the substrate with relatively uniform length. Transmission electron microscope (TEM) observations indicated that the as-grown CNTs were nearly catalyst-free thin-MWCNTs with small outer diameters of less than 10nm.The average wall number is about 5. We suggested a possible growth mechanism of the VA thin-MWCNT arrays. The VA thin-MWCNTs showed a low turn-on electric field of about 1.1 V/μm at a current density of 0.1 μA/cm 2 and a high emission current density about 2.5 mA/cm 2 at a bias field of 2.7 V/μm. Moreover, the VA thin-MWCNTs presented better field emission stability without degradation over 20 hours (h) at the emission current density of about 1 mA/cm 2 .