Nano-scale compositional lamination of doped silica glass deposited in surface discharge plasma of SPCVD technology

The kinetics of metal halogenide mixture transformation into oxides was studied with the help of optical emission spectroscopy (OES) in the microwave-induced discharge of surface plasma chemical vapor deposition (SPCVD) process. The structure of germanium-doped silica layer deposited in plasmachemical synthesis of preforms for optical fiber drawing was also investigated. It was shown that deposited glass has a periodical structure of alternate layers with different glass composition. Observation experiments on the oxide formation kinetics in plasma column were performed for the interpretation of the lamination effect. It was demonstrated that the lamination effect is related to a non-uniform distribution of the corresponding monoxides along the plasma column. This lamination results from the competition of different chemical oxidation reactions for oxygen. On the basis of the results obtained, a set of chemical reactions responsible for the formation of multicomponent glasses in SPCVD-type processes is proposed.