Synthesis of Silane and Silicon in a Non-Equilibrium Plasma Jet. Fourth Quarterly Report, March 21--June 20, 1977

摘要

The feasibility of high volume, low cost production of high purity silane or solar grade silicon using a non-equilibrium hydrogen atom plasma jet was determined. Reactions of hydrogen atoms in the plasma jet with chlorosilanes (added either to the discharge or to the hydrogen atom stream) are being studied. Products of the H/SiCl sub 4 reaction were collected and quantitatively analyzed using a fractionation/distillation-mass spectrometric technique. Conversion of SiCl sub 4 to lower chlorosilanes and solid (Si) was on the order of 10 percent. The percentage conversion was found to depend upon equivalence ratio (ratio of SiCl sub 4 to H concentrations) and reaction zone pressure. Electronic grade reagent SiCl sub 4 gave smaller product yield and different product distribution than did technical grade. Real-time, in situ mass spectrometric sampling of the H/H sub 2 /SiCl sub 4 reaction zone gases was initiated. Quantitative results have not been obtained due to the complexity of the chlorosilane mass spectra, and consequent resolution and sensitivity difficulties with the mass spectrometer. Improvements in the instrumentation needed for these measurements are discussed. The performance of the flower petal nozzle, No. 5 was characterized. Current/voltage behavior was similar to that previously observed in the nozzle-as-anode mode of operation for simpler nozzles. Hydrogen atom yields of approximately 1 percent are obtainable with production efficiencies of approximately 2 to 3 moles H/kWh of discharge energy. A remeasurement of yields and production efficiencies from the simpler nozzle No. 2 confirmed yields of approximately 3 percent for H atoms and production efficiencies of approximately 5 moles H/kWh. Measurements of H-atom yields were found to depend upon reagent mixing conditions, indicating the need to continue investigations of the mixing properties. (ERA citation 03:011838)