Flash lamp annealing of spray coated films containing oxidized or hydrogen terminated silicon nanoparticles

• Silicon nanoparticle suspensions are spray coated on molybdenum substrates.
• Spectroscopic ellipsometry and atomic force microscopy watch the deposition.
• After deposition a light flash anneals the sample to fuse silicon nanoparticles.
• Silicon nanoparticle surface oxidation correlates with the effects of annealing.

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.