6533b835fe1ef96bd129f309

RESEARCH PRODUCT

Role ofH2Oin the thermal annealing of theEγ′center in amorphous silicon dioxide

subject

description

The model for the annealing of a radiation-induced point defect in silica, the ${\text{E}}_{\ensuremath{\gamma}}^{\ensuremath{'}}$ center, is identified in the temperature range $(150--550)\ifmmode^\circ\else\textdegree\fi{}\text{C}$. Thermal treatments in controlled atmospheres of water vapor, oxygen, or helium of irradiated amorphous silicon dioxide are carried out. Direct experimental evidences that the annealing of the ${\text{E}}_{\ensuremath{\gamma}}^{\ensuremath{'}}$ center is caused by a reaction with diffusing water molecules are found. A rate equation system describing this annealing process is inferred, and its solutions are compared with experimental data to obtain quantitative information. In particular, the activation energy, its distribution and the way the latter is modified by thermal treatments are derived. The process was also established to be reaction limited. The mean activation energy value for the annealing process of the ${\text{E}}_{\ensuremath{\gamma}}^{\ensuremath{'}}$ center due to water is found to be 1.23 eV.