Microstructure of Magnetron Sputtered Amorphous SiO<i>_x</i> Films: Formation of Amorphous Si Core−Shell Nanoclusters

Abstract

The microstructures of the as-sputtered amorphous silicon-rich oxide (SiOx) films were investigated by using a combination of X-ray photoelectron spectroscopy (XPS) and Raman microscopy. XPS analysis reveals that the as-sputtered amorphous SiOx films are chemically inhomogeneous. Raman spectra and valence band XPS spectra suggest the formation of amorphous Si nanoclusters in the as-sputtered amorphous SiOx films. The size of these nanoclusters depends on the Si concentration in the films. The formation of amorphous Si nanoclusters was attributed to the high kinetic energy and surface migration of the sputtered Si atoms. It is found that the as-sputtered amorphous SiOx films have a complex structure consisting nanoscale cluster of amorphous Si core with suboxides shell embedded in the amorphous SiO2 matrix.