Preparation of silica glass doped with nitrogen by modified chemical vapor deposition

A thermodynamic analysis of the doping of silica glass with nitrogen by the chemical vapor deposition methods has been carried out. The fundamental differences are revealed between the plasma chemical vapor deposition and modified chemical vapor deposition methods. The basic parameters of nitrogen introduction into silica glass are determined by thermodynamic calculations. It is found that the main factor that ensures doping of silica glass with nitrogen by the modified chemical vapor deposition is an extremely low partial oxygen pressure in the reaction zone. The results of theoretical analysis are used in practice for nitrogenizing silica glass by modified chemical vapor deposition. The increment in the refractive index is equal to 0.0015.