AVS 51st International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS-MoP

Paper PS-MoP7
Experimental Characterization of an Inductively-Coupled Acetylene/Hydrogen Plasma for Carbon Nanofibers Synthesis

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: C. Lin, National Tsing Hua University, Taiwan
Authors: Y.Y. Lin, National Tsing Hua University, Taiwan
K.C. Leou, National Tsing Hua University, Taiwan
H.H. Wei, National Tsing Hua University, Taiwan
M.T. Wei, National Tsing Hua University, Taiwan
C. Lin, National Tsing Hua University, Taiwan
C.H. Tsai, National Tsing Hua University, Taiwan
Correspondent: Click to Email
A plasma enhanced chemical vapor deposition process was employed to synthesiz carbon nanofibers on silicon or glass substrates patterened with Ni catalystic films. The plasma was generated by an inductive coil driven by 13.56 MHz RF power with acetylen and hydrogen gas mixtures. The substrates were placed on a temperature controlled staged which was also powered by 13.56 RF voltages. At gas pressure 15-25 mTorr and substrate temperature (surface) 500-600°C, isolated and vertically-aligned carbon nanofibers have been successfully synthesized. This paper reports experimental investigation of plasma properties characterized by optical emission spectroscopy of spectra line intensities of various species such as hydrogen, C@sub 2@ and CH, as well as RF properties at the biased substrate stage measured by RF impedance meter. Measurement results reveal that line intensity of C@sub 2@ increases with acetylene/hydrogen ratio. On the other hand, hydrogen atom density which was estimated by optical actinometry measurements(using Ar as the tracer gas) decreases accordingly. As a consequence, there was more @alpha@-C contents in the nanofibers as verified by both SEM imagies and micro-Ramman measurements. The ion current(or flux) incident on the substrate surface was estimated by the ratio of the RF power over RF voltage amplitudes as measured by the impedance meter. The ion current increased with ICP source power but changed little when the bias power was varied, as expected. The RF voltage amplitude, which is rougly proportional to ion energy, decreased as ICP power was increased. This is because plasma density increases with source power but the bias power is fixed.