Dresden 2009 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 16: Diffusion and Point Defects I

MM 16.4: Talk

Tuesday, March 24, 2009, 12:15–12:30, IFW B

Defect structures in CaF₂ for optical applications — •Stephan Rix^1,2, Marisa Aigner¹, Claudia Felser², Martin Letz¹, Ute Natura³, and Lutz Parthier³ — ¹Schott AG, Mainz — ²Johannes Gutenberg-Universität, Mainz — ³Schott Lithotec, Jena

Single crystal calcium fluoride (CaF₂) is an important lens material for deep-ultraviolet optics used in microlithographic structuring of semiconductors. High radiation densities require an extreme laser-stability of the material. The quality of the material strongly depends on a high purity level. For long exposure times the optical quality of CaF₂ is affected by radiation-induced defect structures, namely F- and H-centers. The migration and agglomeration of these defect structures play an important role in understanding laser-damage processes on a microscopic level. We use ab-initio methods to investigate the stabilization of laser-induced defects by agglomeration or impurities. As stabilization processes involve defect migration, we also focus on diffusion properties of defects. We present a method for the calculation of diffusion barriers, which shows good agreement with experimental results for the F-center with well localized electronic wave functions.