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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.


Related in: MedlinePlus

Experimentally determined spatial detection profiles. Experimentally determined spatial detection profiles with the big and the small pinhole corrected for the refractive index outside and inside of the sample. The n values refer to the refractive index in silicon and air.
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Figure 1: Experimentally determined spatial detection profiles. Experimentally determined spatial detection profiles with the big and the small pinhole corrected for the refractive index outside and inside of the sample. The n values refer to the refractive index in silicon and air.

Mentions: The requirement for the high resolution of about 1 μm of all of the discussed techniques is to measure under high injection conditions, since the carrier diffusion length has to be in the order of the spatial resolution or lower. This is typically the case only under high injection conditions, where Auger recombination limits the diffusion length to 1 μm or less. The physical principle behind the quantitative determination of doping density and Shockley-Read-Hall lifetime by μPLS is to measure the depth profile of the injection density and to compare the measurement with simulations. The depth profile is measured by varying the pinhole size of the confocal microscope, which allows to measure with different spatial detection profiles. We execute two measurements with a pinhole size of 100 and 1,000 μm, respectively. The detection profiles of both pinhole sizes are experimentally determined by scanning a pre-breakdown site with a diameter of less than 550 nm (Figure 1).


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)

Experimentally determined spatial detection profiles. Experimentally determined spatial detection profiles with the big and the small pinhole corrected for the refractive index outside and inside of the sample. The n values refer to the refractive index in silicon and air.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Experimentally determined spatial detection profiles. Experimentally determined spatial detection profiles with the big and the small pinhole corrected for the refractive index outside and inside of the sample. The n values refer to the refractive index in silicon and air.
Mentions: The requirement for the high resolution of about 1 μm of all of the discussed techniques is to measure under high injection conditions, since the carrier diffusion length has to be in the order of the spatial resolution or lower. This is typically the case only under high injection conditions, where Auger recombination limits the diffusion length to 1 μm or less. The physical principle behind the quantitative determination of doping density and Shockley-Read-Hall lifetime by μPLS is to measure the depth profile of the injection density and to compare the measurement with simulations. The depth profile is measured by varying the pinhole size of the confocal microscope, which allows to measure with different spatial detection profiles. We execute two measurements with a pinhole size of 100 and 1,000 μm, respectively. The detection profiles of both pinhole sizes are experimentally determined by scanning a pre-breakdown site with a diameter of less than 550 nm (Figure 1).

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