Fig. 2: STEM and EELS characterization of 2D IF layer.

a A STEM-ADF image of IF layer is grown on WSe₂ substrate. The scale bar is 20 nm. b EEL spectra of the IF layer (red spectrum) and WSe₂ substrate (blue spectrum) taken from the brighter layer and the dark region in (a), respectively. c A closeup of the yellow rectangle area in (a), which shows a moiré pattern of the surface IF layer with the WSe₂ substrate. The scale bar is 2 nm. d An FFT pattern of the whole image in (a), where the left part marked with red and blue circles in the diffraction spots showing a clear epitaxial relationship of the surface IF layer and the WSe₂ substrate.