Dresden 2011 – scientific programme
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DF: Fachverband Dielektrische Festkörper
DF 6: Optical and nonlinear optical properties, photonic
DF 6.2: Talk
Tuesday, March 15, 2011, 11:00–11:20, MÜL Elch
Temperature dependent absorption and Urbach tail scaling in LuAG single crystals. — •Martin Letz1, Alexander Gottwald2, Matthias Richter2, Vlad Liberman3, and Lutz Parthier1 — 1Schott AG, Hattenbergstr. 10, 55128 Mainz — 2Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin — 3Lincoln Laboratory. MIT, 244 Wood St., Lexington, Massachusetts 02420-9108, USA
In the deep ultraviolet (DUV) spectral range the transmission of high purity Lu3Al5O12, LuAG was measured using monochromatized synchrotron radiation. In the vicinity of the band gap below 7.8 eV, a scaling behavior of the absorption as a function of photon energy was observed. Temperature dependent measurements [1] allow us to distinguish different absorption mechanisms which differ by their ability to couple to phonon excitations. Interpreting the Urbach tails measured at different temperatures, we show that the temperature independent tail is due to defects in the lattice, whereas the temperature dependent part originates from the short term localization of exciton modes coupling to lattice distortions. These results allow us to extrapolate the maximum transmittance which can be obtained with LuAG crystals at the lithographic wavelength of 193.39 nm. Accurate determination of the maximum transmission limit is critical in deciding whether the material can meet industry’s specification for 193-nm-based high index lithography.
[1] M.Letz, A.Gottwald, M.Richter, V.Liberman, L.Parthier, Phys. Rev. B, 81, 155109 (2010)