Influence of plasma condition on carbon nanotube growth by rf-PECVD

Abstract

Carbon nanotubes (CNTs) have been synthesized from Ar-CH 4 mixtures using rf-plasma enhanced chemical vapor deposition (rf-PECVD) at 500 o C. Reduction gases such as H 2 and NH 3 were found unnecessary for carbon nanotube formation compared to thermal CVD. The relationship between the growth of CNTs and the plasma condition in PECVD has been investigated by in situ self bias measurement. Plasma conditions were controlled by changing the interelectrode distance, rf power and the applied substrate negative bias. By increasing the interelectrode distance and rf power, the spatial density of CNTs was on a rise as a result of the increase in ions density and self bias. As the applied substrate negative bias increased, the spatial density of CNTs decreased possibly due to the positive ions over bombarding effect.

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“…16,23,24) The increase in V oc is mainly due to the weakening Ar plasma bombardment power density on the sloping grown surface of Si-pyramids during the deposition of PECVD-VGNWs. 25) The rectification ratio of a diode is the ratio of its current at forward voltage to its current at reverse voltage. Rectification ratio is the direct expression of the specificity of one-way electric conduction of the diode, the higher the better.…”

Confirming the key role of Ar+ ion bombardment in the growth feature of nanostructured carbon materials by PECVD

“…No negative dc bias was applied to the lower electrode. Moreover, through a voltmeter, we could ascertain that the self-bias voltage on the substrate was nearly negative 20 V under our experimental conditions [25].…”

Patterned growth of vertically aligned carbon nanotube arrays using colloidal lithography and plasma enhanced chemical vapor deposition

“…Carbon nanotubes were synthesized with the growth temperature of 500 •C, a rf power M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 4 of 50W and a 5:2 flow of argon and ethylene gases in a homemade rf-PECVD reactor which is described in detail elsewhere [22]. The growth time was varied from 5 min to 45 min in order to clarify the patterned growth mechanism by colloidal lithography and PECVD.…”