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Potential and limitations of epitaxial emitters

 
: Rachow, T.; Milenkovic, N.; Heinz, F.; Breitwieser, M.; Steinhauser, B.; Janz, S.; Reber, S.

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Fulltext urn:nbn:de:0011-n-2669090 (370 KByte PDF)
MD5 Fingerprint: 9c3ecf847c23595f64f93068abefdb61
Created on: 7.12.2013


Mine, A. ; European Commission:
28th European Photovoltaic Solar Energy Conference and Exhibition, EU PVSEC 2013. Proceedings. DVD-ROM : 30 September to 04 October 2013, Paris, France
München: WIP-Renewable Energies, 2013
ISBN: 3-936338-33-7
pp.827-830
European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC) <28, 2013, Paris>
English
Conference Paper, Electronic Publication
Fraunhofer ISE ()
Materialien - Solarzellen und Technologie; Silicium-Photovoltaik; Herstellung und Analyse von hocheffizienten Solarzellen; Formation; Epitaxy; CVD Deposition

Abstract
Reducing the total costs of modules by increasing the efficiency of solar cells is one of the major challenges in today’s photovoltaic research. The emitter epitaxy by atmospheric pressure chemical vapour deposition (APCVD) offers a cost-efficient and faster alternative to the standard furnace diffusion process. The epitaxial emitter formation at 1050 °C only takes 1-2 min whereas the diffusion process using POCl3 takes up to 60 min. The purpose of this work is to show the potential of epitaxial grown emitters compared to diffused emitters. PC1D simulations show an increase in voltage of VOC = + 10 mV and a reduction in saturation current J0e of 30% for the epitaxial emitter. These advantages are due to lower surface recombination velocity and reduction of Auger recombination of the optimised emitter profile. The lifetime experiments including an epitaxial emitter show a diffusion length Leff of 750 μm and an emitter saturation current of J0e = 46 fA/cm² on a planar 10 cm p-type FZ wafer. Another important aim of this work is to determine the limitations of epitaxial emitters due to thermal degradation of the base material, interface recombination and the change of reflective properties on textured wafers due the deposition process. In a first batch, solar cell efficiencies up to 18.4 % underline that emitter epitaxy by APCVD is a competitive process for the emitter formation.

: http://publica.fraunhofer.de/documents/N-266909.html