Figure 52.

Identification of exfoliated layer numbers. (A) Optical contrast map of a representative CrI₃ flake (left) and the corresponding optical contrast per number of layers (right).⁵ Adapted with permission from ref (5). Copyright 2017 Springer Nature. (B) Left: Optical image of few-layer flakes of MnBi₂Te₄ exfoliated onto Al₂O₃. The corresponding layer number is labeled on selected flakes. The scale bar is 20 μm. Right: MnBi₂Te₄ transmittance versus layer number.¹¹¹ Adapted with permission from ref (111). Copyright 2020 AAAS. (C) Optical image of few-layer Fe₃GeTe₂ flakes exfoliated onto Al₂O₃.¹² (D) AFM image of the area in (C) marked by a solid black square.¹² The scale bar is 2 μm. (E) Height profile plotted versus length along the white line in (D).¹² Panels (C–E) are adapted with permission from ref (12). Copyright 2018 Springer Nature.