ABSTRACTS
Fourier Transform InfraRed absorption spectroscopy of a dusty SiH4/Ar plasma
G. Dingemans, M. Cavarroc*, J. Remy, W.W.Stoffels, G.M.W.Kroesen , Eindhoven University of Technology Applied physics dept, den Dolech 2 PO Box 513, 5600 MB Eindhoven, The Netherlands – EU
*Current address: GREMI, Université d'Orléans, B.P. 6744, 45067 Orléans Cedex 2 France – EU
Plasma deposition is used in the industry for manufacturing solar sells. Despite this practical application, little is known about the particle formation and growth process in this silane-based plasma. In order to gain insight in this mixing of molecules and nano-particles, infrared absorption spectroscopy is a useful aid. The frequencies at which particles absorb in the infrared region actually characterize their vibrational transitions. Measurements similar to the ones performed by Kroesen et al in [1] are made. The set-up is based on a Fourier transform spectrometer, which is coupled to a capacitively-coupled plasma, typically operating at low-pressures between 100 mTorr and 1 Torr. We study the presence and the time dependant concentration of transient species such as SiH or SiH2. FTIR is also used to analyze the solid-state by-products that are generated with our plasma. The poster not only displays latest measurements and an overview of the set-up being used, it also illustrates the performances of our FTIR/plasma chamber coupling through an acetone spectrum. [1] Kroesen et al, In situ infrared absorption spectroscopy of dusty plasmas, J.Vac.Sci.Technol.A 14(2), 1996
Mode tuning and Cavity Ring Down Spectroscopy. Preliminary results to the analysis of dusty plasma
J. Remy, W.W.Stoffels, G.M.W.Kroesen , Eindhoven University of Technology Applied physics dept, den Dolech 2 PO Box 513, 5600 MB Eindhoven, The Netherlands – EU
Under most conditions, dust particles are generated in a radio-frequency silane plasma. Cavity Ring-Down Spectroscopy (CRDS) is a diagnostic technique of particular relevance in the study of the optical absorption of those dust particles. Our CRDS experimental design is actually based on 0.1 mW continuous-wave (CW) multimode lead-salt laser diodes emitting in the mid-infrared wavelength range. In order to use CRDS with those laser diodes, we have developed a novel simple ring-down technique that does not require the laser to be turned on and off at a specific moment. That method, called “mode tuning”, uses the ring-down cavity mode structure as well as the optical properties of the laser diode itself in order to control the ring-down decay. The work presented here shows that cavity ring-down spectroscopy has the potential to measure the dynamics of all radicals relevant in the particle nucleation process. The poster also demonstrates that a controlled detuning of the laser diode proves to be a non-intrusive way of stopping the infrared beam.
This work is supported by the European Union as part of the H-Alpha project under contract NNE5-1999-004 and by the Dutch Centrum voor Plasmafysica en Stralingstechnologie