Reactions of SiCl groups in amorphous SiO2 with mobile interstitial chemical species:: Formation of interstitial Cl2 and HCl molecules, and role of interstitial H2O molecules -: art. no. 043515

Reactions of the network-bound chloride (SiCl) groups in amorphous SiO2 (a-SiO2 or SiO2 glass) with mobile interstitial oxygen (O-2), water (H2O), and hydrogen (H-2) molecules thermally loaded from ambient atmosphere and with mobile radicals created by exposure to F-2 laser light (lambda=157 nm,h nu=7.9 eV) were investigated. Reactions of the SiCl groups with O-2 and H2O produce interstitial chlorine (Cl-2) and hydrogen chloride (HCl) molecules, respectively. An infrared-absorption band appearing at similar to 2815 cm(-1) is assigned to the interstitial HCl. The SiCl groups do not react with H-2 below 400 degrees C. However, sequential gas loading first with O-2, then with H-2 leads to the production of interstitial H2O, which decomposes the SiCl groups into HCl. Furthermore, the formation of the interstitial HCl with exposure to F-2 laser light, most likely due to the cracking of the Si-Cl bonds with photogenerated hydrogen atoms (H-0), was demonstrated. These findings yield a general picture of the reactions of the chlorine-related species in a-SiO2 and demonstrate the significant influence of even minor amounts (< 10(18) cm(-3)) of interstitial H2O on defect formation and annihilation processes. (c) 2005 American Institute of Physics.