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Formation of silicon nanowire packed films from metallurgical-grade silicon powder using a two-step metal-assisted chemical etching method.

Ouertani R, Hamdi A, Amri C, Khalifa M, Ezzaouia H - Nanoscale Res Lett (2014)

Bottom Line: 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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratoire de Photovoltaïque, Centre de Recherches et des Technologies de l'Énergie, Technopôle de Borj-Cédria, BP 95, 2050 Hammam-Lif, Tunisie.

ABSTRACT
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.

No MeSH data available.


SEM micrograph of the starting powder.
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Figure 2: SEM micrograph of the starting powder.

Mentions: The chemical reagents used in this work were hydrofluoric acid (HF; 40%), silver nitrate (AgNO3), hydrogen peroxide (H2O2; 30%), nitric acid (HNO3; 65%), and ethanol (C2H5OH; 65%). All of them were purchased from Sigma-Aldrich Corporation (St. Louis, MO, USA) and used without any purification, whereas metallurgical-grade polycrystalline silicon powder was obtained from Aremco Products Inc. (Valley Cottage, NY, USA). Prior to any treatment, the grain size distribution (GSD) of the received powder was measured with a Malvern Instruments Mastersizer 2000 (Malvern Instruments, Malvern, UK) using the laser scattering method. The powder is composed of polyhedral silicon micrograins (SiμGs) having a quite large grain size distribution. As depicted in Figure 1, the measurement has shown that the GSD of the starting Si powder ranges from 1 to 120 μm.Morphologies of silicon powder before and after chemical etching were characterized by SEM (JEOL JSM-5400, JEOL Ltd., Akishima-shi, Japan). Prior to SEM observation, a small amount of the treated Si powder was glued to a copper plate with a silver ink. SiμG dimension has been estimated from the SEM micrograph displayed in Figure 2. The values confirm in some way the Malvern Mastersizer measurements. It was revealed that the SiμGs have got random polyhedral shapes.


Formation of silicon nanowire packed films from metallurgical-grade silicon powder using a two-step metal-assisted chemical etching method.

Ouertani R, Hamdi A, Amri C, Khalifa M, Ezzaouia H - Nanoscale Res Lett (2014)

SEM micrograph of the starting powder.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4209156&req=5

Figure 2: SEM micrograph of the starting powder.
Mentions: The chemical reagents used in this work were hydrofluoric acid (HF; 40%), silver nitrate (AgNO3), hydrogen peroxide (H2O2; 30%), nitric acid (HNO3; 65%), and ethanol (C2H5OH; 65%). All of them were purchased from Sigma-Aldrich Corporation (St. Louis, MO, USA) and used without any purification, whereas metallurgical-grade polycrystalline silicon powder was obtained from Aremco Products Inc. (Valley Cottage, NY, USA). Prior to any treatment, the grain size distribution (GSD) of the received powder was measured with a Malvern Instruments Mastersizer 2000 (Malvern Instruments, Malvern, UK) using the laser scattering method. The powder is composed of polyhedral silicon micrograins (SiμGs) having a quite large grain size distribution. As depicted in Figure 1, the measurement has shown that the GSD of the starting Si powder ranges from 1 to 120 μm.Morphologies of silicon powder before and after chemical etching were characterized by SEM (JEOL JSM-5400, JEOL Ltd., Akishima-shi, Japan). Prior to SEM observation, a small amount of the treated Si powder was glued to a copper plate with a silver ink. SiμG dimension has been estimated from the SEM micrograph displayed in Figure 2. The values confirm in some way the Malvern Mastersizer measurements. It was revealed that the SiμGs have got random polyhedral shapes.

Bottom Line: 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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratoire de Photovoltaïque, Centre de Recherches et des Technologies de l'Énergie, Technopôle de Borj-Cédria, BP 95, 2050 Hammam-Lif, Tunisie.

ABSTRACT
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.

No MeSH data available.