Ambient gas-induced SiC-like structures in edge-defined film-fed grown polycrystalline silicon samples

Abstract

Several techniques were used to study a surface layer structure of edge-defined film-fed grown polycrystalline silicon samples grown in CO gas deliberately added to the purging atmosphere. Although infrared analysis reveals the presence of cubic SiC structures, other techniques, such as spectroscopic ellipsometry and Raman spectroscopy, do not detect its presence. It is concluded that a layer with specific structure, formed in the course of ribbon growth, consists of indiffused oxygen formed upon reaction of CO gas with molten Si. Indiffused oxygen, in turn, induces coaggregation of carbon and silicon selfinterstitials that probably play the role of SiC nucleation centres, but do not have the thermal stability of SiC.