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Micro-spectroscopy on silicon wafers and solar cells.

Gundel P, Schubert MC, Heinz FD, Woehl R, Benick J, Giesecke JA, Suwito D, Warta W - Nanoscale Res Lett (2011)

Bottom Line: This is demonstrated on micro defects in multicrystalline silicon.In comparison with the stress measurement by μRS, these measurements reveal the influence of stress on the recombination activity of metal precipitates.With the aim of evaluating technological process steps, Fano resonances in μRS measurements are analyzed for the determination of the doping density and the carrier lifetime in selective emitters, laser fired doping structures, and back surface fields, while μPLS can show the micron-sized damage induced by the respective processes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Fraunhofer Institute for Solar Energy Systems (ISE), Heidenhofstr, 2, 79110 Freiburg, Germany. paul.gundel@ise.fraunhofer.de.

ABSTRACT
Micro-Raman (μRS) and micro-photoluminescence spectroscopy (μPLS) are demonstrated as valuable characterization techniques for fundamental research on silicon as well as for technological issues in the photovoltaic production. We measure the quantitative carrier recombination lifetime and the doping density with submicron resolution by μPLS and μRS. μPLS utilizes the carrier diffusion from a point excitation source and μRS the hole density-dependent Fano resonances of the first order Raman peak. This is demonstrated on micro defects in multicrystalline silicon. In comparison with the stress measurement by μRS, these measurements reveal the influence of stress on the recombination activity of metal precipitates. This can be attributed to the strong stress dependence of the carrier mobility (piezoresistance) of silicon. With the aim of evaluating technological process steps, Fano resonances in μRS measurements are analyzed for the determination of the doping density and the carrier lifetime in selective emitters, laser fired doping structures, and back surface fields, while μPLS can show the micron-sized damage induced by the respective processes.

No MeSH data available.


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Hole density dependence of q and Γ. (a) Hole density (doping density) against 1,000 × q-1·q-1 is proportional to the hole density. The doping element (aluminum and boron) has no significant effect on the calibration. (b) Hole density (doping density) against line width Γ. The fit shows a quadratic dependence of Γ on the hole density.
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Figure 4: Hole density dependence of q and Γ. (a) Hole density (doping density) against 1,000 × q-1·q-1 is proportional to the hole density. The doping element (aluminum and boron) has no significant effect on the calibration. (b) Hole density (doping density) against line width Γ. The fit shows a quadratic dependence of Γ on the hole density.

Mentions: with the Fano asymmetry parameter q and the line width Γ. Γ and q-1 increase monotonically with the hole density [15] and thus, can be used to measure the hole density. To calibrate both parameters with the hole density, we measured the Raman spectra of samples with known doping densities at 0.7 mW laser power on the sample and fitted the first order Raman peak with equation 1. From the fits, we can extract the hole density dependence of q and Γ (Figure 4).


Micro-spectroscopy on silicon wafers and solar cells.

Gundel P, Schubert MC, Heinz FD, Woehl R, Benick J, Giesecke JA, Suwito D, Warta W - Nanoscale Res Lett (2011)

Hole density dependence of q and Γ. (a) Hole density (doping density) against 1,000 × q-1·q-1 is proportional to the hole density. The doping element (aluminum and boron) has no significant effect on the calibration. (b) Hole density (doping density) against line width Γ. The fit shows a quadratic dependence of Γ on the hole density.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211253&req=5

Figure 4: Hole density dependence of q and Γ. (a) Hole density (doping density) against 1,000 × q-1·q-1 is proportional to the hole density. The doping element (aluminum and boron) has no significant effect on the calibration. (b) Hole density (doping density) against line width Γ. The fit shows a quadratic dependence of Γ on the hole density.
Mentions: with the Fano asymmetry parameter q and the line width Γ. Γ and q-1 increase monotonically with the hole density [15] and thus, can be used to measure the hole density. To calibrate both parameters with the hole density, we measured the Raman spectra of samples with known doping densities at 0.7 mW laser power on the sample and fitted the first order Raman peak with equation 1. From the fits, we can extract the hole density dependence of q and Γ (Figure 4).

Bottom Line: This is demonstrated on micro defects in multicrystalline silicon.In comparison with the stress measurement by μRS, these measurements reveal the influence of stress on the recombination activity of metal precipitates.With the aim of evaluating technological process steps, Fano resonances in μRS measurements are analyzed for the determination of the doping density and the carrier lifetime in selective emitters, laser fired doping structures, and back surface fields, while μPLS can show the micron-sized damage induced by the respective processes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Fraunhofer Institute for Solar Energy Systems (ISE), Heidenhofstr, 2, 79110 Freiburg, Germany. paul.gundel@ise.fraunhofer.de.

ABSTRACT
Micro-Raman (μRS) and micro-photoluminescence spectroscopy (μPLS) are demonstrated as valuable characterization techniques for fundamental research on silicon as well as for technological issues in the photovoltaic production. We measure the quantitative carrier recombination lifetime and the doping density with submicron resolution by μPLS and μRS. μPLS utilizes the carrier diffusion from a point excitation source and μRS the hole density-dependent Fano resonances of the first order Raman peak. This is demonstrated on micro defects in multicrystalline silicon. In comparison with the stress measurement by μRS, these measurements reveal the influence of stress on the recombination activity of metal precipitates. This can be attributed to the strong stress dependence of the carrier mobility (piezoresistance) of silicon. With the aim of evaluating technological process steps, Fano resonances in μRS measurements are analyzed for the determination of the doping density and the carrier lifetime in selective emitters, laser fired doping structures, and back surface fields, while μPLS can show the micron-sized damage induced by the respective processes.

No MeSH data available.


Related in: MedlinePlus