Rendering Ti₃C₂T_x (MXene) monolayers visible

Abstract

Herein we report on how to render Ti3C2Tx (MXene) monolayers deposited on SiO2/Si wafers, with different SiO2 thicknesses, visible. Inputting the effective thickness of a Ti3C2Tx monolayer (1 ± 0.2 nm) measured by atomic force microscopy, and its refractive index into a Fresnel-law-based simulation software, we show that the optical contrast of Ti3C2Tx monolayers deposited on SiO2/Si wafers depends on the SiO2 thickness, number of MXene layers, and the light’s wavelength. The highest contrast was found for SiO2 thicknesses around 220 nm. Simulations for other substrates, namely, Al2O3/Si, HfO2/Si, Si3N4/Si and Al2O3/Al, are presented as supplementary information.