Single layer films and a multilayer structure of SRO (Silicon Rich Oxide) have been prepared by LPCVD (Low Pressure Chemical Vapour Deposition) and characterized by FTIR, SIMS, XPS, TEM and AFM measurements. The stacked structure is composed of alternating layers of SRO with high Si content and SRO with low Si content. The layered structure is confirmed by SIMS and TEM measurements. The composition of the materials is discussed. Besides Si nanocrystals, the existence of agglomerates of silicon oxide with structure close to fused silica and the existence of oxynitrides is evidenced in the films with high Si content.