Facile Projection of Spatially Resolved Refractive Index Modulation in Monolayer MoS2 via Light Phase Changes

Abstract

Fast spatial contouring of the complex refractive index (n + ik) of semiconducting materials is a much sought-after goal since the advent of semiconductor-related industries. This study develops a novel metrology to shape the refractive index modulation of materials using hyperspectral phase microscopy by maximizing the light-matter interaction of physical properties. The facile, non-destructive, and wide-field hyperspectral phase technique realizes efficient visualization of the spatially resolved refractive index nature induced by strain within and among examined MoS2 materials. Furthermore, numerical analyses based on a steady-state transfer matrix clarify that the spectral phase difference (Delta phi) is selectively sensitive to the modulation of refractive index (n) but not of extinction coefficient (k) under certain wavelength ranges. This dependence is associated with wavelength and the thickness of the dielectric layer on the substrates. Simple linear relation between n and Delta phi for approximate to 100 nm of SiO2, dielectric material supporting MoS2, enables to visualize the excitonic A and B band modulation, and furthermore, refractive index with fairly high precision (coefficient of determination, R-2 > 0.97 in the wavelength range of 530-630 nm).