SURFACE-ANALYSIS OF CLEAVED SINGLE-CRYSTALLINE CASI2 BY AUGER-ELECTRON SPECTROSCOPY

The cleaved CaSi2 (111) plane exhibited atomically smooth terraces with steps, and the secondary electron microscope (SEM) image showed a dark and bright contrast on the terrace. The Auger intensities showed a clear contrast corresponding to the SEM image contrast: The intensity of Si LVV was high in the dark region and low in the bright region, while the intensity of Ca LMM was reversed. The surface termination of the cleaved CaSi2 (111) was quantitatively determined from the Auger-electron-spectroscopy point analysis such that the dark region was terminated in the Si bilayer and the bright region in the Ca monolayer. The results show that the cleavage occurs between the Ca monolayer and Si bilayer.