Figure 4.

Optical properties of MBE MoS₂. Plots of the measured and calculated MBE MoS₂ ellipsometric parameters (a) Ψ and (b) Δ. (c) Optical constants (n and k) of epitaxial monolayer MoS₂ grown on a sapphire substrate from SE analysis of panels (a,b). For the tabular data, see Table A1. For comparison, we added optical constants of CVD and exfoliated MoS₂ from ref. [37,38], respectively. (d) Measured (red line) and calculated (black line) transmittance spectra of MBE MoS₂ on sapphire matching perfectly within spectrophotometer accuracy (1%) except in the 250–270 nm range, where inaccuracy approaches 2% attributed to the low signal sensitivity of our ellipsometer in that interval. The inset is a refractive index of exfoliated, MBE, and CVD MoS₂ at 750 nm.