Compositional information from amorphous Si-Ce multilayers using high-resolution electron microscopy imaging and direct digital recording

A simple method for extracting compositional information from high-resolution electron microscopy images of an amorphous two-element system using a slow-scan CCD camera has been developed. The method has been evaluated on amorphous Si/Ge multilayers. The characterisation of the multilayers provided information about thickness of the layers, maximum concentrations within the layers and elemental profiles across the boundaries. It was shown that the intensity profiles could be corrected for the wedge shape of the specimen and that the derived compositional profile was independent of average sample thickness variation within the range of the cross-section sample thickness. The results have been compared to analysis performed by Auger electron spectroscopy depth profiling on as-prepared multilayers as well as by energy-dispersive X-ray analysis and electron energy filtered images of cross-sections. The proposed HREM image contrast evaluation method gave spatial resolution in chemical analysis across the thin layers comparable in accuracy to the other methods, whereas the oscillation amplitude for the concentration is slightly less due to specimen preparation artifacts.