Fig. 2: Transmission electron microscopy (TEM) analysis of the abnormal grain growth of MoTe2 accompanied by the phase transition.
a Optical microscopy image and b low-magnification scanning-TEM (STEM) image of the MoTe2 homojunction transferred to the TEM grid, where the two polymorphs are distinguished by the contrast. c Selected area electron diffraction (SAED) pattern captured at the interface between 2H- (blue circles) and 1T’-MoTe2 (yellow rings). Three-fold diffraction spots of 2H-MoTe2 suggest that the corresponding structure is single-crystalline. In contrast, 1T’-MoTe2 is polycrystalline, as demonstrated by the ring shape of the patterns. d SAED patterns of the 2H-MoTe2 measured at the marked regions in (a). e High-resolution STEM image of the homojunction interface (marked as a red circle in (b)). Inset shows the corresponding fast-Fourier-transform (FFT) pattern, showing the three distinct lattices of MoTe2 (orange and green rectangles for the 1T’ and blue hexagon for the 2H structure). f–h (top) Atomic-resolution STEM images of the different grains in (e). The inset on the right shows the computed atomic images for corresponding structures. (bottom) Corresponding FFT patterns of the top images represent the different structures of each grain. The orientation of the three grains was random (Supplementary Fig. 9).
