Infrared diode laser absorption spectroscopy of C(2)H(2) and C(2)H(6) in capacitively coupled methane RF discharges.
Low-temperature RF discharges with methane as feed gas are widely used for the deposition of hydrogenated films. The film properties depend strongly on the chemical composition and therefore two of the main stable products in this kind of discharge, namely ethane (C(2)H(6)) and acetylene (C(2)H(2)), have been measured for the understanding of the reaction kinetics in the plasma. An absorption spectrometer has been built up for the investigation of the concentrations of these as a function of the input power and the flow rate. The time scales for reaching steady state after the discharge is switched on and the depletion time scale after the plasma is switched off have been determined. Assuming the recombination of CH(3) molecules to be the only production mechanism for C(2)H(6) and using a simplified rate equation, the measured densities of C(2)H(6) can be reproduced very well by analytical fitting curves.
Serdioutchenko
A
A
Institute for Experimental Physics V, Ruhr-University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany. serdioutchenko@ep5.ruhr-uni-bochum.de
Möller
I
I
Soltwisch
H
H
D000114:Acetylene / Q000737:chemistry*; D004980:Ethane / Q000737:chemistry*; D007834:Lasers; D008697:Methane / Q000737:chemistry*; D013057:Spectrum Analysis / Q000295:instrumentation; D013997:Time Factors
D004980:Ethane; D000114:Acetylene; D008697:Methane