Kazim Shafaq, Gunnella Roberto, Zannotti Marco, Giovannetti Rita, Klimczuk Tomasz, Ottaviano Luca
Physics Division, School of Science and Technology, University of Camerino, Camerino, MC, Italy.
Department of Chemistry, School of Science and Technology, University of Camerino, Camerino, MC, Italy.
J Microsc. 2021 Aug;283(2):145-150. doi: 10.1111/jmi.13015. Epub 2021 May 17.
Based on previous reports on the optical microscopy contrast of mechanically exfoliated few layer CrCl transferred on 285 nm and 270 nm SiO on Si(100), we focus on the experimental determination of an effective mean complex refractive index via a fitting analysis based on the Fresnel equations formalism. Accordingly, the layer and wavelength-dependent absorbance and reflectance are calculated. Layer and wavelength-dependent optical contrast curves are then evaluated demonstrating that the contrast is significantly high only around well-defined wavelength bands. This is validated a posteriori, by experimental UV-Vis absorbance data. The present study aims to show the way towards the most reliable determination of thickness of the 2D material flakes during exfoliation.
基于先前关于转移到Si(100)上的285 nm和270 nm SiO₂ 上的机械剥离少层CrCl₃ 的光学显微镜对比度的报道，我们专注于通过基于菲涅耳方程形式的拟合分析来实验确定有效平均复折射率。据此，计算了与层数和波长相关的吸光度和反射率。然后评估了与层数和波长相关的光学对比度曲线，结果表明仅在明确的波长带附近对比度才显著较高。这通过实验紫外可见吸光度数据事后得到了验证。本研究旨在展示在剥离过程中最可靠地确定二维材料薄片厚度的方法。
