SURFACE-DEFECTS OF MOS2 CRYSTAL OBSERVED BY SCANNING LEED MICROSCOPY

Crystal defects in the MoS2 surface were observed by dark field images in scanning LEED microscopy [T. Ichinokawa et al., Surf. Sci. 176 (1986) 397]. Regularly arranged triangular defects of dark contrast were observed in dark field images of a specular or non-specular spot in the LEED patterns at a primary energy of 1 keV, a beam current of 10-12 A and an angle of incidence 75° from the surface normal. The length of the side of the triangular defects is 0.4 micro m and the density of the number of triangles is 1.9 × 108/cm2 on the surface. These defects are attributed to stacking faults produced by a hexagonal network of screw dislocations lying between the 1st and 2nd layer in the surface. On account of the broadening of the diffraction spots and the increase of background in the selected area micro-diffraction pattern from the stacking fault areas, the dark contrast of the triangles is attributed to the lattice distortion of the 1st layer inside the stacking faults. This distortion is caused by the shear stress of the screw dislocations surrounding the stacking faults which correspond to extended triangular nodes of a screw dislocation network. © 1990.