THERMAL ANNEALING BEHAVIOR OF ION-IMPLANTED SILICA GLASS

Infrared reflection spectra have been measured in silica glasses which are initially damaged by 2 MeV O+- and 1.5 MeV C+-ion implantations then isothermally annealed at 200, 300, 400, 500 and 600-degrees-C. Thermal annealing effects on Si-O-Si bond angles have been deduced from the peak wavenumber shift of the 1100 cm-1 band in the infrared reflection spectra. The relaxation of Si-O-Si bond angles obeys the stretched exponential decay function with beta ranging from 0.28 to 0.15. It is deduced that the relaxation of Si-O-Si bond angles has a distribution of activation energies. The major relaxation mechanism of Si-O-Si bond angles has an activation energy of 118 kl/mol. It is inferred that the relaxation of Si-O-Si bond angle is due to a small movement of SiO4 tetrahedra without the disruption of Si-O bonds.