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N-type and P-type silicon foils fabricated in a quasi-inline EPI reactor with bulk lifetimes exceeding 500 µs

: Janz, S.; Milenkovic, N.; Drießen, M.; Reber, S.

Fulltext urn:nbn:de:0011-n-3791173 (562 KByte PDF)
MD5 Fingerprint: 0ad4bac579fe3f7e82b6bdb434b6a3b4
Created on: 5.3.2016

European Commission:
31st European Photovoltaic Solar Energy Conference and Exhibition, EU PVSEC 2015 : 14 to 18 September 2015, Hamburg, Germany
Hamburg, 2015
ISBN: 3-936338-39-6
European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC) <31, 2015, Hamburg>
Conference Paper, Electronic Publication
Fraunhofer ISE ()
Materialien - Solarzellen und Technologie; Silicium-Photovoltaik; Kristalline Silicium-Dünnschichtsolarzellen; Based Deposition; epitaxy; high deposition rate; porous silicon

In this publication we present free standing p- and n-type Si layers with thicknesses between 40 μm (EpiFoils) and 150 μm (EpiWafers) produced with epitaxy on electrochemically etched porous Si layers followed by mechanical lift-off. We show that reorganization and epitaxy in our quasi-inline tool leads to Si layers with very good crystal quality (etch pit density around 1000 cm-2) and low contamination levels (interstitial Fe concentration around 1010 cm-3). Thin p-type foils with just 40 μm thickness show minority carrier lifetimes of up to 80 μs mainly limited by a high dopant concentration of 5x1016 cm-3. The n-type epitaxial wafers with 150 μm thickness reach average minority carrier lifetimes of more than 1.5 ms. Appearing inhomogeneity of minority carrier lifetimes over the sample area are found to be due to surface cleaning process but not bulk quality related issues. The excellent lifetimes together with the very constant dopant concentration of our Si layers is sufficient for high efficiency solar cell architectures and a conversion efficiency of 20 % can be exceeded.