A variety of silicon nanoparticle (Si NP) powders is studied with diffuse-reflectance infrared Fourier-transform spectroscopy before and after treatment with hydrofluoric acid. As received Si NPs and surface passivated Si NPs are dispersed in organic dispersion media such ethanol. A spray coating system is used to spray the Si NPs onto molybdenum substrates under nitrogen atmosphere. During film growth an in-line spectroscopic ellipsometer monitors the deposition process. In addition, a Xe-lamp enables to flash films in order to melt Si NPs together. Si NP films are then investigated using atomic force microscopy, scanning electron microscopy, and Raman spectroscopy. Eventually, a difference in surface termination (e. g. state of surface oxidation and hydrogen passivation) between Si NP amounts of three selected providers was found. Furthermore, the dispersion stability of Si NP powder in dry ethanol (>99%), the film roughness after processing, and the melting of Si NP films is found to depend strongly on the surface termination of the NPs. (C) 2014 Elsevier B.V. All rights reserved.