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arXiv · 2502.21241

Unambiguous determination of optical constants and thickness of ultrathin films by using optical anisotropic substrates

Sebastian Schaper·Matthias Duwe·Ursula Wurstbauer
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Abstract

The unambiguous and universal determination of optical constants such as complex refractive indices (n, k) and thickness (d) in one measurement is typically confined for films with a thickness of more than 10~nm that hampers its application for ultra-thin films such as two-dimensional materials. We demonstrate that the commonly accepted limit of n, k, d coupling is overcome in ellipsometry by utilizing anisotropic substrates. In this way, ellipsometry allows to determine n, k and d simultaneously for thicknesses lower than 1~nm with high accuracy. Extensive simulations proof the potential of using anisotropic substrates for decoupling. The simultaneous determination of n, k and d is of great interest in several fields, two-dimensional materials, their heterostructures, ultra thin films for application in quantum technology, plasmonics and nano-photonics.

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Sebastian Schaper, Matthias Duwe, Ursula Wurstbauer. 2025-02-28. Unambiguous determination of optical constants and thickness of ultrathin films by using optical anisotropic substrates. https://arxiv.org/abs/2502.21241

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