In this work, we use a two-step metal-assisted chemical etching method to produce films of silicon nanowires shaped in micrograins from metallurgical-grade polycrystalline silicon powder. The first step is an electroless plating process where the powder was dipped for few minutes in an aqueous solution of silver nitrite and hydrofluoric acid to permit Ag plating of the Si micrograins. During the second step, corresponding to silicon dissolution, we add a small quantity of hydrogen peroxide to the plating solution and we leave the samples to be etched for three various duration (30, 60, and 90 min). We try elucidating the mechanisms leading to the formation of silver clusters and silicon nanowires obtained at the end of the silver plating step and the silver-assisted silicon dissolution step, respectively. Scanning electron microscopy (SEM) micrographs revealed that the processed Si micrograins were covered with densely packed films of self-organized silicon nanowires. Some of these nanowires stand vertically, and some others tilt to the silicon micrograin facets. The thickness of the nanowire films increases from 0.2 to 10 μm with increasing etching time. Based on SEM characterizations, laser scattering estimations, X-ray diffraction (XRD) patterns, and Raman spectroscopy, we present a correlative study dealing with the effect of the silver-assisted etching process on the morphological and structural properties of the processed silicon nanowire films.

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Silicon nanowires (SiNWs), with different ratios, have been elaborated by metal assisted chemical etching (MACE) on P3HT:SiNWs blends, deposited onto PET substrate. X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and hotoluminescence (PL) measurements have been used to control the structural, morphological and optical properties of the investigated structure. The best concentration chosen is followed by an annealing treatment. Our results prove that the optimal structure is obtained with the nanocomposite P3HT:SiNWs (1:1). The moderate annealing temperature, around 90 °C, is most appropriate. A correlation between XRD, AFM and PL measurements can explain the decrease of charge transfer and the coupled of SiNWs with increasing concentration. Our results can improve the possibility to integrate those kinds of structures as an active layer in the photovoltaic applications.

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