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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.

The decay constants of the a1Δg(v=0)→X3Σg-(v=0) infrared photoluminescence (PL) of isotopically-labeled oxygen molecules 16O18O and 18O2 dissolved in the interstitial voids of a-SiO2 are ∼1.7 and ∼2.5 times larger than that of 16O2. This difference originates from the isotope shift in the energy of the nonradiative transitions from the a state to the vibronic levels of the X ground state. Calibration of the PL quantum yield using the measured decay constants is essential to measure the correct concentration of isotopically-labeled interstitial O2.

Time decay of photoluminescence due to interstitial oxygen molecules (O2) in synthetic amorphous SiO2(a-SiO2) was studied by varying the fictive temperature and the concentrations of common dopants (SiOH, SiCl, and SiF groups). The decay constant is insensitive to the fictive temperature, but strongly depends on the type of dopants: it is reduced by the nonradiative decay via an energy transfer from O2 to the vibrational modes of the dopants. The increases in the nonradiative decay rate due to SiOH, SiF, and SiCl groups are strong, slight, and negligible, respectively, which correlates with their vibrational energies. The quantum yield decreases by ∼20% as the SiOH content increases from 1017 to 1020cm−3. The deviation from the single exponential decay is due to the shape variation in the a-SiO2 network cages that surround O2, and to the distance distribution between O2 and SiOH groups.

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