Interstitial oxygen molecules in amorphous SiO2. III. Measurements of dissolution kinetics, diffusion coefficient, and solubility by infrared photoluminescence

Concentration changes of interstitial oxygen molecules (O2) in amorphous SiO2(a-SiO2) thermally annealed in oxygen atmosphere were examined by the O2 photoluminescence at 1272 nm excited with 765-nm light of titanium sapphire laser. This highly sensitive technique allows the time- and temperature-dependent concentration changes of interstitial O2 due to their incorporation from an oxygen atmosphere to be directly measured. The data provide the dissolution rate, the diffusion coefficient, and the solubility of interstitial O2 in a-SiO2 and are able to exclude interferences from other forms of mobile oxygen species in a-SiO2. These observations confirm that O2 molecules are incorporated into a-SiO2 without separating into monoatomic species, diffuse in a-SiO2 without extensive interaction with the a-SiO2 network, and play a primary role in the thermal oxidation of silicon.