Measuring the Refractive Index of Highly Crystalline Monolayer MoS2 with High Confidence

Abstract

Monolayer molybdenum disulphide (MoS 2 ) has attracted much attention, due to its attractive properties, such as two-dimensional properties, direct bandgap, valley-selective circular dichroism, and valley Hall effect. However, some of its fundamental physical parameters, e.g. refractive index, have not been studied in detail because of measurement difficulties. In this work, we have synthesized highly crystalline monolayer MoS 2 on SiO 2 /Si substrates via chemical vapor deposition (CVD) method and devised a method to measure their optical contrast spectra. Using these contrast spectra, we extracted the complex refractive index spectrum of monolayer MoS 2 in the wavelength range of 400 nm to 750 nm. We have analyzed the pronounced difference between the obtained complex refractive index spectrum and that of bulk MoS 2 . The method presented here is effective for two-dimensional materials of small size. Furthermore, we have calculated the color contour plots of the contrast as a function of both SiO 2 thickness and incident light wavelength for monolayer MoS 2 using the obtained refractive index spectrum. These plots are useful for both fundamental study and device application.

Imaging spectroscopic ellipsometry of MoS2

“…Finally, the lateral homogeneity of the dielectric function is investigated for a large area monolayer MoS2 on sapphire. [26,39,40]. It is obvious that the optical contrast in Fig.…”

Modulating Photoluminescence of Monolayer Molybdenum Disulfide by Metal–Insulator Phase Transition in Active Substrates

“…Using such two‐step simulations, we could get the relative PL power for all desired layer thicknesses and temperature combinations. Here, we used refractive indexes of MoS 2 , BN and dielectric constants of VO 2 at 30 °C (insulating) and 85 °C (metallic) in literature as the values in our simulation.…”

Origin of Improved Optical Quality of Monolayer Molybdenum Disulfide Grown on Hexagonal Boron Nitride Substrate

“…Figure a is 3D contour plot of the corresponding result normalized by the calculated PL intensity of control sample (namely, the enhancement factor Γ). The refractive index of h‐BN is 2.13, and that of monolayer MoS 2 is adopted from our previous work . The 3D curved surface shows the close dependence of Γ on the h‐BN thickness.…”