XPS study of ion-beam-assisted formation of Si nanostructures in thin SiO2 layers

Thin thermally grown SiO2 layers have been enriched with Si up to similar to15 at.% by Si ion implantation at room temperature. X-ray photoelectron spectroscopy (XPS) was used to monitor the composition changes caused in the layers by bombardment with 3 keV Ar ions at elevated temperatures. Argon ion irradiation of pure SiO2 does not lead to the formation of Si nanoprecipitates. That was the case also for room-temperature Ar bombardment of Si-rich layers. Their 'hot' irradiation with Ar ions was found to enhance considerably the formation of segregated Si nanophase inclusions. The process starts at similar to500degreesC and becomes strongly pronounced at 650degreesC. At this temperature ion-beam-induced crystallization of Si nanoprecipitates may be achieved. The results obtained are explained in the framework of the physical model, based on the irradiation-enhanced diffusion of excess Si atoms. Copyright (C) 2002 John Wiley Sons, Ltd.