Structural defect control and photosensitivity in reactively sputtered germanosilicate glass films

Barrett G. Potter, Kelly Simmons-Potter, W. L. Warren, Judith A. Ruffner, Dorothy C. Meister

Research output: Contribution to journalConference article

Abstract

The optical performance of refractive index structures induced in photosensitive (PS) glasses ultimately depends on the index modulation depth attainable. In germanosilicate materials, the photosensitive response is linked to the presence of oxygen-deficient germanium point defect centers. Prior efforts to increase PS in these materials, e.g., hydrogen loading, rely on a chemical reduction of the glass structure to enhance the population of oxygen deficient centers and thus increase the saturated refractive index change. We have previously reported the development of highly photosensitive, as-deposited germanosilicate glass films through reactive atmosphere (O2Ar) sputtering from a Ge/Si alloy target. The present work details our investigation of the effect of substrate temperature during deposition on the material structure and propensity for photosensitivity. Using optical absorption/bleaching, Raman, electron paramagnetic resonance (EPR) and selective charge injection techniques we show that the predominate defect states responsible for the PS response can be varied through substrate temperature control. We find that two regimes of photosensitive behavior can be accessed which exhibit dramatically different UV-bleaching characteristics. Thus, the corresponding dispersion of the refractive index change as well as its magnitude can be controlled using our synthesis technique. Tentative defect models for the photosensitive process in materials deposited at both ambient temperature and at elevated substrate temperatures are presented.

Original languageEnglish (US)
Pages (from-to)146-153
Number of pages8
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume2998
DOIs
StatePublished - Dec 1 1997
EventPhotosensitive Optical Materials and Devices - San Jose, CA, United States
Duration: Feb 12 1997Feb 12 1997

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Keywords

  • Germanosilicate
  • Glass
  • Photosensitivity
  • Point defects
  • Reactive atmosphere sputtering
  • Thin film

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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