GROWTH AND ATOMIC STRUCTURE OF ULTRATHIN COBALT LAYERS ON THE Cu(111) FACE CLEAN AND PRECOVERED WITH LEAD

The growth and atomic structure of ultrathin Co layers deposited on the clean Cu(111) face and precovered with about 0.7 ML of Pb were investigated with the use of Auger electron spectroscopy and directional elastic peak electron spectroscopy (DEPES). Auger spectra for the clean Cu (111) face and covered with 1.5 ML of Co indicate the growth of cobalt bilayer islands sunk at one-monolayer depth in the substrate and covered with one monolayer of copper. The ratio of M2,3VV cobalt and copper Auger peak heights increases with cobalt coverage faster for the Pb -precovered Cu(111) face than for the clean surface. DEPES profiles reveal the threefold symmetry of the cobalt layer up to 4.5 ML. For higher coverages, an arrangement of a sixfold symmetry appears, indicating the presence of fcc(111) cobalt domains rotated 60° with respect to the substrate (i.e. growing after a stacking fault abcbac) separated from the abcabc domains by the bcb layer with the hcp structure.

Auger valence electron spectra in Ca-silicides

CaSi2 and CaSi have been investigated by Auger Valence Electron Spectroscopy (AVES). Some drastic differences of the Auger peak due to 3s states in the Si atoms were observed in the Si[2s, 2p, V] Auger spectra. The peak that arised from valence electron states in the Ca atoms was observed in the Ca[2p, 3p, V] Auger spectra for both Ca-silicides. This result suggests that the Ca–Si bonds are partially ionic. However, the number of the valence electrons in Ca atoms for CaSi was larger than that for CaSi2. This result implies that the part of homopolar bonds between the Si and Ca atoms in CaSi is stronger than that in CaSi2. Based on these results, it has been concluded that the change of the Si [2s, 2p,V] Auger spectra is associated with the difference of the part of homopolar bonds between the Si and Ca atoms.

Auger Electron Spectroscopy of The CVD Diamond Surface Under Electron Exposure

ABSTRACTA simultaneous study of Auger spectra and secondary electron emission from the chemical vapor deposited diamond films under extended electron beam exposure is presented. Up to a 1.2 eV increase in energy of the carbon Auger peak accompanied by the decrease of the total secondary electron yield has been found. Exposure to hydrogen has resulted in recovery of the both Auger peak position and secondary yield. First-principles electronic structure calculations have been carried out to interpret the Auger peak shift. The effect is shown to be due to a change in the surface upper-valence band local density of states of the diamond crystal which is dependent on the extent of hydrogen coverage of the surface.