BEHAVIOR OF ULTRATHIN LAYERS OF CO ON SI AND GE SYSTEMS

Photoelectron spectroscopic study of the interaction of Co with Ge sur face is reported for the first time. The behavior of ultrathin layers of Co on Ge(100) has been compared with that on Si(100) surfaces based on ultraviolet and X-ray photoelectron spectroscopic studies (UPS and XPS). Formation of silicides and germanides take place upon depositin g Co on clean Si(100) and Ge(100) surfaces, respectively. at room temp erature. The Co 2p transition is observed at a slightly higher binding energy in the case of silicide (778.7 +/- 0.2 eV) compared to that of the germanide (778.1 +/- 0.2 eV). Upon annealing the Co covered surfa ces, the Co atoms diffuse into the bulk and the onset temperature of i nward diffusion is low in Ge (similar to 150 degrees C) compared to th at in Si (similar to 350 degrees C). Go-deposition of Co and Ge on cle an Ge(100) surface at room temperature leads to the formation of a mix ture of different germanide phases.