Thermal-Protective and Oxygen-Resistant Nanocoating Using Silica-Nanocomposites for Laser Thinning of Polymorphic Molybdenum Ditellurides

Abstract

Laser irradiation has been investigated as a method of fabricating atomically-thin crystals from layered two-dimensional (2D) materials with precise thickness control. However, during laser irradiation, inevitable structural changes can occur in the 2D materials due to the high thermal energy, altering their physical and chemical properties and introducing disorder, which has hindered the study and use of the intrinsic properties of atomically-thin materials. In this study, we report a laser thinning method using a new coating material, a layered silica-based nanocomposite (SNC), that preserves the pristine crystal structure of a polymorphic 2D material, MoTe2, down to an atomically thin geometry. The nano-porous coating of layered silica-based nanocomposite (SNC) was robust against thermal heating and behaved as a good thermal-protective and oxygen-resistant material in the laser thinning process. Therefore, the SNC-coated MoTe2 flakes were successfully thinned down to atomically-thin geometry, while preserving their 2H structure. Accordingly, our SNC coating of 2D materials is a promising way to engineer the phase and geometry of polymorphic 2D materials, enabling versatile applications in various optoelectronic, spintronic, and electronic devices.

Keywords: Transition metal dichalcogenides, Fe(III)-TA coating, Laser-thinning, phase transition, thickness control