Dependence of defects induced by excimer laser on intrinsic structural defects in synthetic silica glasses

Abstract

Effects of intrinsic defects on defect formation by excimer-laser irradiation were examined in synthetic silica glasses prepared by different methods. In samples containing oxygen-deficient centers (ODC s), laser-induced E' centers were stable at room temperature. In contrast, in samples heat treated in H, atmosphere, in which almost all ODC's changed into Si -H bonds, the induced-E'-center concentration increased by about two orders of magnitude, and the resulting E' centers were unstable, decaying at room temperature. We thus conclude that the formation efficiency of E' centers from Si -H bonds is much higher than that of ODC's and that the induced-E' centers recombine with radiolytic molecular H~to restore Si -H bonds. It is suggested that a trace amount of Si -H bonds plays an essential role in defect creation and annihilation in OH-containing silica glasses.

Nd:YAG laser induced E′ centers probed by in situ absorption measurements

“…This band is one of the main contribution to the degradation of the optical transmittance of silica glasses in several applications such as optical fibers or components in lasers. Several studies have pointed out that the generation of E' center upon laser exposure is associated with the transformation of native precursor center via different mechanisms controlled by one-or two-photons absorption [5][6][7][8][9]. On the other side, in a recent work based on room temperature isothermal annealing experiments, we evidenced that a fraction of photoinduced E' centers in natural silica are passivated in the post irradiation stage through diffusion-limited reactions with molecular hydrogen H 2 [10].…”

Densification of sol-gel thin films by ultraviolet and vacuum ultraviolet irradiations

“…Thus, the cross section at 8.0 eV for a hydroxyl group in Sit2 gel was estimated to be "-~2.3 • 10 -18 cm z. The absorption tail due to hydroxyl groups in SiO2 glass was also reported above "-~8 eV [15,16]. The cross section at 8.0 eV estimated for Sit2 glass, ~1.7 x 10 -zs cm z [15] is almost the same as that for SiO2 gel.…”

Photoelectric threshold of silicon wafer surfaces implanted with H, Si and Ar ions

“…This annihilation of the E center for the H-implanted samples may be associated with the formation of Si-H bond with an increase in the concentration of H atoms. [14] Figure 5 shows the dependence of the amount of total photoelectrons counted in the spectral yield curve (hereafter referred to as PE total count) at three different temperatures on the concentration of the implanted atoms. Clearly the ion-implanted samples show an increase in the PE total count compared to the nonimplanted sample, more strongly at 340…”