Thickness identification of two-dimensional materials from optical microscopy images

Hsiao-Ching Yu^1*, Yi-Ying Lu¹

¹物理系物理研究所, 國立中山大學, 高雄市, Taiwan

* Presenter:Hsiao-Ching Yu, email:wendy602017@gmail.com

Two-dimensional materials are promising for making novel devices of electronics and photonics, as they exhibit many new optoelectronic properties that are different from bulk materials. Since the properties of a 2D material often depend on its thickness, identification of thickness is crucial. Although thickness of a thin material can be accurately measured by an AFM, the measurement not only is time-consuming but also might cause damage to the sample surface. By the analysis of reflection and transmission of light from multilayer films based on the Fresnel equations, we develop a method of estimating the thickness of a sample flake by assessing the optical contrast between the apparent colors of the flake and the substrate imaged by an optical microscope. This method provides a handy rapid estimation of thickness, albeit with accuracy slightly comprised. Particularly, applied to 2D materials of InSe, it yields satisfactorily accurate estimations of thickness in the range of 20-30nm.

Keywords: semiconductors, semiconductor physics, low-dimensional semiconductors