DETERMINATION OF EFFECTIVE ENERGY-LOSS FUNCTIONS AND X-RAY PHOTOELECTRON-SPECTROSCOPY SOURCE FUNCTIONS FOR SI 2P PHOTOELECTRONS FROM CLEAN SI(111), OXYGEN-ADSORBED SI(111) AND SIO2 SURFACES

Effective energy loss functions for Si 2p photoelectrons were determin ed for the thermally cleaned Si(111), oxygen-adsorbed Si(111) and SiO2 surfaces by the analysis of the reflection electron energy loss spect roscopy (REELS) spectra using the extended Landau theory. The backgrou nd subtraction of the Si 2p x-ray photoelectron spectroscopy (XPS) spe ctra using these effective energy loss functions has enabled the XPS s ource functions to be derived with considerable effectiveness. This re sult has indicated that the effective energy loss functions derived fo r the clean Si(111) surface are significantly affected by the oxygen a dsorption and the XPS source functions from the clean and oxygen-adsor bed Si(111) surfaces show a small hump due to the chemical shift by th e oxygen adsorption appearing at the tail of the lower kinetic energy side of the Si 2p peak from the oxygen-adsorbed Si surface. On the SiO 2 surface, the analysis of the REELS spectrum has yielded the effectiv e energy loss function reflecting the fine structures which were not a s clearly observed in the measured REELS spectrum. The Si 2p XPS sourc e function determined for the SiO2 surface at two,different measuring geometries showed very good agreement with each other. This study stro ngly suggests that the present analysis is very informative for the st udy of the initial oxidation of the silicon surface (C) 1998 American Institute of Physics.