Silicon Rich Oxide (SRO) is a dielectric material that contains Si nanoparticles, thus showing novel physical characteristics which permits its use in optoelectronic devices. In this work, the composition and structure at the surface, volume and Si/SRO interface of the SRO films deposited on c-Si substrates were studied. Different techniques, such as Atomic Force Microscopy (AFM), High Resolution Transmission Electronic Microscopy (HRTEM), Rutherford Backscattering Spectrometry (RBS) and X-ray Photoelectron Spectroscopy (XPS) were used in the study. XPS and RBS reveal that the composition of the films varied with respect to the gas flow ratio. These results allow us to correlate the compositional and structural [as size of the grains (roughness), nc-Si size and different oxidation states of Si] changes of the surface, volume and interface from the SRO films with the flow ratio (Ro) used during the deposition process and with the high temperature annealing time.