Laser-patterned 2D transparent amorphous phase

Abstract

Fabricating disordered solids at atomic-scale thickness at the desired area is challenging because of the high energy cost of weakening the covalent bonds. Here, we demonstrate a low-power laser-patterning of a transparent amorphous phase on a two-dimensional transition metal chalcogenide alloy. Laser irradiation induces selective evaporation of elements in the crystalline 2H-Mo_0.92W_0.08Te₂ (c-2H), resulting in the progressive phase transformation from crystalline 2H to amorphous MoWTe (a-MoWTe) phase with an intermediate polycrystalline 1T’-Mo_0.92W_0.08Te_2-x (p-1T’). The a-MoWTe has multi-valent cations of Mo⁵⁺, W⁴⁺, and W⁶⁺, indicating that the local chemical environments of a-MoWTe are different from those of c-2H. The multi-valence states of cations could result in a significant lattice disorder by changing the coordination numbers, leading to the phase transformation from crystalline to amorphous phase. Our laser-patterned 2D amorphous phase enables a practical application for next-generation nanoelectronics and photonics, energy storage/conversion, and sensors.