Spectroscopic Ellipsometry for Two-Dimensional Materials: Methods, Optical Modeling, and Emerging Phenomena

TL;DR

This review highlights spectroscopic ellipsometry as a versatile, non-destructive technique for characterizing the optical properties of 2D materials, revealing phenomena like anisotropy and hyperbolic dispersion crucial for device applications.

Contribution

It provides a comprehensive overview of ellipsometric methods, optical modeling, and recent discoveries in 2D materials, emphasizing advanced techniques like Mueller matrix ellipsometry.

Findings

Detection of extreme optical anisotropy in 2D materials

Observation of hyperbolic dispersion phenomena

Identification of tunable plasmonic responses

Abstract

Spectroscopic ellipsometry (SE) has emerged as a powerful and non-destructive optical characterization technique for probing the complex dielectric properties of two-dimensional (2D) materials. This review provides a comprehensive overview of ellipsometric methods applied to atomically thin and multilayer van der Waals materials, including graphene, transition metal dichalcogenides, and other emerging 2D systems. We discuss experimental configurations, optical modeling strategies, and challenges associated with reduced dimensionality, anisotropy, and substrate effects. Advanced techniques such as Mueller matrix ellipsometry are highlighted for their capability to resolve in-plane and out-of-plane dielectric tensor components in anisotropic and low-symmetry materials. Furthermore, we review recent discoveries enabled by ellipsometry, including extreme optical anisotropy, hyperbolic dispersion, and tunable plasmonic responses in multilayer 2D materials. These findings establish spectroscopic ellipsometry as an essential tool for both fundamental studies and photonic device engineering based on two-dimensional materials.