Regensburg 2022 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 20: Poster

DS 20.18: Poster

Mittwoch, 7. September 2022, 16:00–18:00, P3

Spectroscopic Ellipsometry of transition metal oxide thin films — •Nahid Ahmadian^1,2, Teresa I. Madeira^1,2, and Dietrich R.T. Zahn^1,2 — ¹Chemnitz University of Technology, Chemnitz, Germany — ²Center for Materials, Architectures and Integration of Nanomembranes (MAIN), D-09107, Chemnitz, Germany

Transition metal oxides such as HfO₂ or TiO₂ with bandgaps of 5.3-5.9 eV and 3.0-3.4 eV, are transparent in the visible range of the spectrum, i.e. their extinction coefficient in this range is very low close to zero while the refractive index varies as a function of photon energy. In this work, we tested four dispersion models: Sellmeier, Cauchy, extended Cauchy, and Tauc-Lorentz aiming at understanding the mathematical and physical differences of these approximations, their robustness and limitations in addressing amorphous and crystalline phases of thin films of HfO₂ deposited by atomic layer deposition (ALD) on Si(100) and TiO₂ thin films prepared on Si(100) by magnetron sputtering and spin coating. The spectroscopic ellipsometry measurements were performed using a M-2000 T-Solar from J.A. Woollam. Spectra covering a range of energies 0.7 (IR) − 5 eV (UV) were taken in air at room temperature and analyzed using CompleteEASE. We conclude that multiple oscillators are required to treat the crystalline phases in comparison to the amorphous, and when very good solutions are obtained from all oscillators, the choice to use one or the other is based on complexity: the less the fit parameters the best.