A review of optics-based methods for thickness and surface characterization of two-dimensional materials

Two-dimensional (2D) materials have attracted great attention because of their unique physical properties and versatile applications in electronics and photonics. Following the trends of large-area 2D materials-based devices and systems implementation, large-area, high-throughput thickness and surface characterization techniques are required. Optics-based thin film characterization techniques have promising advantages in fast characterization speed, contactless large-area probing, and highly accurate measurement results. In this review, we overview optics-based methods for thickness and surface characterization of various 2D materials, including the use of optical reflection contrast, Raman spectroscopy, photoluminescence, optical interference effects, phase-shifting interferometry, nonlinear optical harmonic generations, and spectroscopic ellipsometry.