Thermochemical Nanolithography and Hot-Plate Heating of 2D MoS₂ and CrSBr Flakes in Air

We extend thermochemical nanolithography (TCNL) capabilities toward thermally induced modifications of thin MoS₂ and CrSBr flakes in air. We perform atomic force microscopy studies and thermal TCNL calibration with Raman spectroscopy as well as analytic heat-flow models. While TCNL cannot provide a high enough temperature to thermally oxidize and etch the basal planes of such flakes, it can deform the underlying Si and SiO₂ substrates and pattern the surfaces of 2D materials in some specific cases. In particular, TCNL enables thermally induced deposition of Cr oxides/hydroxides onto CrSBr basal planes in a new, reverse patterning scheme. It is also able to pattern already oxidized MoS₂ layers. In addition, the microscopic oxidation of CrSBr crystals has been studied upon their hot-plate heating. Thick CrSBr flakes start to oxidize at around 330 °C, while thin ones etch above 350 °C. Their oxidation leads to the formation of surface-bound Cr(III) oxides and/or hydroxides, as well as some sulfates.