Development of a Microspot Spectroscopic Ellipsometer Using Reflective Objectives, and the Ellipsometric Characterization of Monolayer MoS2

  • Received : 2020.02.04
  • Accepted : 2020.05.11
  • Published : 2020.08.25


Adopting an elaborately designed reflective objective consisting of four mirrors, we have developed a rotating-polarizer-type microspot spectroscopic ellipsometer (SE) with an ultra-small spot size. The diameter of the focused beam, whether evaluated using a direct-image method or a knife-edge method, is less than 8.4 ㎛. After proper correction for the polarizing effect of the mirrors in the reflective objective, we unambiguously determine the dispersion of the complex refractive index and the thickness of monolayer MoS2 using the measured microspot-spectroellipsometric data. The measured ellipsometric spectra are sensitive enough to identify small variations in thickness of MoS2 flakes, which ranged from 0.48 nm to 0.67 nm.



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