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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

Hole density and lifetime values in the BSF. The Raman-Fano-measured hole density in the BSF (p+-layer) (a) and the resulting effective Shockley-Read-Hall lifetime at high injection (b). Lifetime values greater than 200 ns mean that the lifetime is solely limited by Auger recombination.
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Figure 5: Hole density and lifetime values in the BSF. The Raman-Fano-measured hole density in the BSF (p+-layer) (a) and the resulting effective Shockley-Read-Hall lifetime at high injection (b). Lifetime values greater than 200 ns mean that the lifetime is solely limited by Auger recombination.

Mentions: The SRH lifetime measurement along a line scan through the BSF (p+-layer) of a monocrystalline silicon solar cell is exemplified here. The doping density profile was measured with electrochemical capacitance voltage and is taken into account in the simulation for the lifetime determination. The lifetime within the BSF is crucial for the solar cell performance. An average value was determined to be 120 ns by Schmidt et al. [17]. For our spatially resolved measurements, we use μRS on a cross section of the BSF. The measured hole density in the BSF at a laser power of 27 mW is depicted in Figure 5a.


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 and lifetime values in the BSF. The Raman-Fano-measured hole density in the BSF (p+-layer) (a) and the resulting effective Shockley-Read-Hall lifetime at high injection (b). Lifetime values greater than 200 ns mean that the lifetime is solely limited by Auger recombination.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Hole density and lifetime values in the BSF. The Raman-Fano-measured hole density in the BSF (p+-layer) (a) and the resulting effective Shockley-Read-Hall lifetime at high injection (b). Lifetime values greater than 200 ns mean that the lifetime is solely limited by Auger recombination.
Mentions: The SRH lifetime measurement along a line scan through the BSF (p+-layer) of a monocrystalline silicon solar cell is exemplified here. The doping density profile was measured with electrochemical capacitance voltage and is taken into account in the simulation for the lifetime determination. The lifetime within the BSF is crucial for the solar cell performance. An average value was determined to be 120 ns by Schmidt et al. [17]. For our spatially resolved measurements, we use μRS on a cross section of the BSF. The measured hole density in the BSF at a laser power of 27 mW is depicted in Figure 5a.

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