The aim of this work is to study the properties of a silicon-based deposit realized with a glow dielectric barrier discharge at atmospheric pressure in a nitrogen, silane and nitrous oxide mixture. It is shown that a continuous thin film can be realized. The chemical composition of the thin layer has been determined by x-ray photoelectron spectroscopy and static secondary ion mass spectrometry. The characteristics of the deposit are correlated to those of the discharge. The first steps of a chemical pathway leading to the precursors of the deposit are proposed from the analysis of the optical emission spectrum of the discharge. It appears that, unlike the low-pressure PECVD in a N₂O-SiH₄ mixture, in an atmospheric-pressure glow discharge NO is the main oxidizing species, due to the action of the metastable nitrogen molecules.