The emission effect of metal-tip removal in carbon nanotubes by bias-assisted ICPHFCVD

Abstract

This paper presents a technique for the preparation of vertically grown carbon nanotubes (CNTs) by bias-assisted inductively coupled plasma hot-filament chemical vapor deposition. Purification of the CNTs using r.f. plasma in a one-step process, based on the different etching property of the metal tip is also discussed. The Ni at the tip of the CNTs was effectively removed by using r.f. plasma based on the different etching property. After purification CNTs show the multi-walled and hollow-type structure. The measured critical current density on CNTs with a Ni tip was 3.52×10⁻⁷ A cm⁻² at 2.47 V μm⁻¹ turn-on field and 6.6×10⁻⁴ A cm⁻² at 4.8 V μm⁻¹ of the critical field. On the other hand, the critical current density on purified CNTs after Ni removal by an r.f. source was 1.36×10⁻⁷ A cm⁻² at 2.1 V μm⁻¹ turn-on field and 1.5×10⁻³ A cm⁻² at 6 V μm⁻¹ of the critical field, respectively.