2025/02/28 by Schaper, Sebastian, Duwe, Matthias, Wurstbauer, Ursula
#FOS: Physical sciences #Optics (physics.optics)
paper · doi:10.48550/arxiv.2502.21241
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.