Interference-Modulated Excitonic Reflectance of Monolayer MoSe₂ on Epitaxial Gd₂O₃ Thin Films

Abstract

We report on the excitonic resonance reflectance characteristics of MoSe 2 monolayers (MLs) exfoliated on epitaxial Gd 2 O 3 (111)/Si(111) thin films. We demonstrate that the reflectance of MoSe 2 MLs can be modulated by varying the thickness of the epitaxial Gd 2 O 3 layer. Upon increasing the Gd 2 O 3 layer thickness from 6 to 50 nm, the resonance reflectance modulation increases by 3-fold and the line-shape changes from Lorentzian to asymmetric Fano-like resonance. We demonstrate that the observed phenomena are a direct consequence of multiple reflections of light within the dielectric layer that interferes with the excitonic Lorentzian oscillator.