A STUDY OF SI COMPOUNDS BY ZR L-ALPHA PHOTOELECTRON-SPECTROSCOPY

Zirconium La radiation has been utilized to investigate the chemical b onding in silicon compounds by x-ray photoelectron spectroscopy. The c ompounds studied in the present investigation are SiO2, SiO, SiC, Si3N 4, and silicon-oxynitrides. The spectra in the Si Is and KLL Auger reg ions were recorded for these compounds and compared with the elemental spectra. In order to estimate the change in chemical environment of S i in these compounds, the Auger parameter was determined in each case as the difference between the binding energies for the Is and the KLL peaks. The trend in the value of the Auger parameter is correlated wit h the degree of atomic relaxation due to the increasing neutralization of charge around the Si cations in these compounds. A good agreement was found between the change in the Auger parameter and the bond ionic ity calculated for the Si cation in these compounds. Using this plot, the bond ionicities were determined for the oxynitrides. A model is al so developed to estimate these ionicities from the concentrations of o xygen and nitrogen present in these compounds. The values of the ionic ities obtained by these two different methods give a satisfactory agre ement. We have shown that the plot between the change in the Auger par ameter and the bond ionicity could be used to estimate the bond ionici ties. (C) 1996 American Vacuum Society.