Fig. 3

Atomic structure of monolayer MoS_2−x Te _x with Te–S species. a Low-magnification TEM image of the tellurized MoS₂ flake on a 1.2-μm hole Cu grid; scale bar, 10 μm. b Electron diffraction pattern from the corresponding positions in (a); scale bars, 5 nm⁻¹. c Another hexagonal phase emerges from 3, revealing the MoTe₂ phase with a 0.340 nm lattice constant, in addition to MoS₂ with a lattice constant of 0.304 nm; scale bar, 5 nm⁻¹. d Schematics for three representative atomic phases of MoS₂, MoS₁Te₁ (Te–S), and MoTe₂. Annular dark field (ADF) STEM image with the corresponding intensity line profile of four species (white circle for S–S, yellow circle for Te–S, red circle for Te–Te, and sky-blue for the Mo site), which is distinguished by brightness; scale bar, 1 nm. e False-color FFT filtered images of regions 1 and 3 in a. Te–S and Te–Te in the chalcogen site marked by a yellow and red circle, respectively; scale bars, 2 nm. f Two types of Te–S arrangement in monolayer MoS₁Te₁ structure. g Analysis of Raman spectrum for MoS_2−x Te _x alloy with calculated vibrational modes of Janus phase and randomly distributed Te–S in monolayer MoS₁Te₁