APPLICATIONS OF ELECTRON HOLOGRAPHY TO THE STUDY OF INTERFACES

Electron holography has been applied to a variety of layered structure s to assess its usefulness for supplying information about composition profiles across heterogeneous interfaces. The phase of the exit-surfa ce electron wave, which to a first approximation is dependent upon the mean inner potential and the specimen thickness, was extracted from e lectron holograms acquired from suitable cross-sectional multilayer sp ecimens. Line profiles from the reconstructed phase images were analyz ed to obtain information about interface diffuseness and layer width w ith a spatial resolution of about 5 angstrom. Using spatial averaging parallel to the interface, increased measurement precision was obtaina ble in some special cases. Differences in interdiffusion widths betwee n Mo-Si and Si-Mo interfaces in an Mo/Si multilayer structure were con firmed, and the width of the amorphous layer at Si3N4 grain boundaries was measured to be about 12 angstrom. It was concluded that off-axis electron holography, represented a useful complementary technique for characterizing interfaces.