Photoemission study of the oxidation and the post-annealing behaviors of a Pr-covered Si(1 0 0) surface

Abstract Electron spectroscopy has been used to investigate the oxidation and the post-annealing behaviors of a Pr/Si surface. The Pr overlayer with a thickness of about 20 A was deposited on Si(1 0 0) at room temperature. It was found that some of the Pr atoms form chemical bonds with Si. An initial fast oxygen adsorption on the Pr/Si surface is mainly associated with the formation of Pr 2 O 3 . The presence of praseodymium enhances the oxidation rate of the substrate. The silicon atoms diffuse from the Pr–Si bonds as well as the substrate into the Pr 2 O 3 layer, forming a Pr–O–Si silicate. SiO 2 was also observed during oxygen adsorption, which was caused by the oxidation of the Pr–O–Si silicate in the vicinity of the top surface. At high oxygen exposures, a slow further oxygen uptake is related to the growth of the Pr–O–Si bond and SiO 2 . Both Pr 2 O 3 and SiO 2 decrease in intensity while the Pr silicate grows with annealing temperature.