Defects in amorphous silica induced with monochromatic VUV rays

Koichi Awazu, Koji Kanehira, Hiroaki Imai, Hiroshi Hirashima

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Photo-induced structural changes in amorphous SiO2 films were examined using undulator radiation which was a monochromatic light source in vacuum ultraviolet (VUV) region. Frequency decrease of the Si-O stretching vibration in infrared absorption spectrum, generation of E′ centers, and increase of chemical etching rate were observed in the irradiated amorphous SiO2 with 14.1 or 17.8 eV rays. These excitation energies correspond to excitations into excited states of the self-trapped exciton in amorphous SiO2. In contrast, no change was observed in amorphous SiO2 when irradiated with 7.2-12.6 eV rays. Frequency decrease can be explained with transition from regular six membered ring (6 Si and 6 O in a loop) to planar three membered ring (3 Si and 3 O in a loop) in amorphous SiO2 network. Planar three membered rings and E′ centers are localized in the region of 5-25 nm from the top surface where chemical etch rate is also enhanced. A discussion of the mechanisms leading to structural change is presented.

Original languageEnglish
Pages (from-to)589-593
Number of pages5
JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
Issue number1-4
Publication statusPublished - 1998 May


  • E′ center
  • IR spectroscopy
  • Silica
  • Undulator radiation

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation


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