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P: Fachverband Plasmaphysik

P 13: Low Pressure Plasmas - Poster

P 13.2: Poster

Dienstag, 6. März 2018, 16:15–18:15, Redoutensaal

Spectroscopic investigations of the silyl radical using a quantum cascade laser — Andy S. C. Nave¹, Andrei V. Pipa¹, Paul B. Davies², Jürgen Röpcke¹, and •Jean-Pierre H. van Helden¹ — ¹Leibniz Institute for Plasma Science and Technology, Greifswald, Germany — ²Department of Chemistry, University of Cambridge, Cambridge, United Kingdom

Silane-based plasma enhanced chemical vapour deposition is an established process for producing hydrogenated amorphous silicon (a-Si:H) films for the solar cell industry. The most abundant product of the fragmentation of SiH4 is the silyl radical, SiH₃, next to other short-lived silicon containing species, such as SiH₂, SiH, Si and related ionic species. The development of increasingly more sensitive spectroscopic techniques to determine the concentration of these short-lived species is essential to enhance our knowledge of the complex chemical processes involved. We report on the measurement of a line strength in the ν₃ fundamental band of the silyl radical using a quantum cascade laser. Rotationally resolved lines of SiH₃ between 2085 and 2175 cm⁻¹ were measured in RF pulsed plasmas containing 10% SiH4 in He and in H2. The line strength of one of these lines, free from interfering transitions, was measured by analysing the radical concentration profile when the discharge was extinguished. The absolute line strength of the silyl radical absorption feature at 2119.947 cm⁻¹ from the ^pP₆(9) transition was determined to be 4.82 ± 2 × 10⁻²¹ cm⁻¹ molecule⁻¹ cm².