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Purification of silicon powder by the formation of thin porous layer followed byphoto-thermal annealing.

Khalifa M, Hajji M, Ezzaouia H - Nanoscale Res Lett (2012)

Bottom Line: Porous silicon has been prepared using a vapor-etching based technique on a commercial silicon powder.Strong visible emission was observed in all samples.Obtained silicon powder with a thin porous layer at the surface was subjected to a photo-thermal annealing at different temperatures under oxygen atmosphere followed by a chemical treatment.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratoire de Photovoltaïque, Centre des Recherches et des Technologies de l'Energie (CRTEn), Technopôle de Borj-Cédria BP 95, Hammam-Lif, 2050, Tunisia. mhajji2001@yahoo.fr.

ABSTRACT
Porous silicon has been prepared using a vapor-etching based technique on a commercial silicon powder. Strong visible emission was observed in all samples. Obtained silicon powder with a thin porous layer at the surface was subjected to a photo-thermal annealing at different temperatures under oxygen atmosphere followed by a chemical treatment. Inductively coupled plasma atomic emission spectrometry results indicate that silicon purity is improved from 99.1% to 99.994% after annealing at 900°C.

No MeSH data available.


Evolution of the maximum of PL intensity and energy at the peak with etching time.
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Figure 3: Evolution of the maximum of PL intensity and energy at the peak with etching time.

Mentions: The photoluminescence properties were obtained using an unfocused argon-ion laser with an excitation wavelength of 488 nm at room temperature. Figure 2 shows the PL spectra of porous silicon elaborated on silicon powder by acid vapor etching method during different etching times. It was found that both the PL intensity and the energy at the peak increase by increasing the etching time (Figure 3). The increase in the intensity is due to an enhancement in the luminescent center density that can be associated to an increase in the thickness of the porous layer [5]. The shift to high energy values is generally attributed to a decrease in the luminescent crystallite size. In this case, the energy at the peak is around 2.05 eV which is higher than values obtained for porous silicon elaborated by the same method on silicon wafers. This shift to higher energies can be attributed to the oxidation of the porous layer. The oxidation leads to the substitution of Si-H bonds by Si-O-H groups and the formation of a Si-SiOx interface, resulting in a blue shift of the PL peak [9,15]. This result is in agreement with the FTIR results that show a very weak band located at 2,050 to 2,200 cm−1 corresponding to SiHn bonds.


Purification of silicon powder by the formation of thin porous layer followed byphoto-thermal annealing.

Khalifa M, Hajji M, Ezzaouia H - Nanoscale Res Lett (2012)

Evolution of the maximum of PL intensity and energy at the peak with etching time.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475061&req=5

Figure 3: Evolution of the maximum of PL intensity and energy at the peak with etching time.
Mentions: The photoluminescence properties were obtained using an unfocused argon-ion laser with an excitation wavelength of 488 nm at room temperature. Figure 2 shows the PL spectra of porous silicon elaborated on silicon powder by acid vapor etching method during different etching times. It was found that both the PL intensity and the energy at the peak increase by increasing the etching time (Figure 3). The increase in the intensity is due to an enhancement in the luminescent center density that can be associated to an increase in the thickness of the porous layer [5]. The shift to high energy values is generally attributed to a decrease in the luminescent crystallite size. In this case, the energy at the peak is around 2.05 eV which is higher than values obtained for porous silicon elaborated by the same method on silicon wafers. This shift to higher energies can be attributed to the oxidation of the porous layer. The oxidation leads to the substitution of Si-H bonds by Si-O-H groups and the formation of a Si-SiOx interface, resulting in a blue shift of the PL peak [9,15]. This result is in agreement with the FTIR results that show a very weak band located at 2,050 to 2,200 cm−1 corresponding to SiHn bonds.

Bottom Line: Porous silicon has been prepared using a vapor-etching based technique on a commercial silicon powder.Strong visible emission was observed in all samples.Obtained silicon powder with a thin porous layer at the surface was subjected to a photo-thermal annealing at different temperatures under oxygen atmosphere followed by a chemical treatment.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratoire de Photovoltaïque, Centre des Recherches et des Technologies de l'Energie (CRTEn), Technopôle de Borj-Cédria BP 95, Hammam-Lif, 2050, Tunisia. mhajji2001@yahoo.fr.

ABSTRACT
Porous silicon has been prepared using a vapor-etching based technique on a commercial silicon powder. Strong visible emission was observed in all samples. Obtained silicon powder with a thin porous layer at the surface was subjected to a photo-thermal annealing at different temperatures under oxygen atmosphere followed by a chemical treatment. Inductively coupled plasma atomic emission spectrometry results indicate that silicon purity is improved from 99.1% to 99.994% after annealing at 900°C.

No MeSH data available.