TY - JOUR

T1 - 4.5 ms Effective Carrier Lifetime in Kerfless Epitaxial Silicon Wafers from the Porous Silicon Process

AU - Gemmel, Catherin

AU - Hensen, Jan

AU - Kajari-Schröder, Sarah

AU - Brendel, Rolf

N1 - Publisher Copyright: © 2011-2012 IEEE. Copyright: Copyright 2018 Elsevier B.V., All rights reserved.

PY - 2017/3

Y1 - 2017/3

N2 - Kerfless silicon wafers epitaxially grown on porous silicon (PSI) and subsequently detached from the growth substrate are a promising candidate for reducing the cost of the silicon wafer, which is particularly important for silicon photovoltaics. However, the carrier lifetime of these epitaxial wafers has to be at least as high as that of today's standard Czochralski (Cz)-grown wafers in order to become competitive. Here, we compare the measured lifetimes of n-type epitaxial silicon wafers that grow on PSI and epitaxial silicon wafers that grow on nonporous surfaces of epi-ready wafers. The latter are subsequently ground to have free-standing epitaxial wafers. Gettering improves the carrier lifetime of the ground wafers up to 4.2 ms. In contrast, PSI wafers show regions with effective lifetimes of 4.5 ms, even without gettering. This lifetime value is a factor of four larger than lifetimes of Cz wafers which are typically employed in today's PERC solar cells. We model the lifetime measurements with three Shockley-Read-Hall (SRH) defects: two defects that exist in the PSI and in the epi-ready wafer and a third defect that is only present in the epi-ready wafer.

AB - Kerfless silicon wafers epitaxially grown on porous silicon (PSI) and subsequently detached from the growth substrate are a promising candidate for reducing the cost of the silicon wafer, which is particularly important for silicon photovoltaics. However, the carrier lifetime of these epitaxial wafers has to be at least as high as that of today's standard Czochralski (Cz)-grown wafers in order to become competitive. Here, we compare the measured lifetimes of n-type epitaxial silicon wafers that grow on PSI and epitaxial silicon wafers that grow on nonporous surfaces of epi-ready wafers. The latter are subsequently ground to have free-standing epitaxial wafers. Gettering improves the carrier lifetime of the ground wafers up to 4.2 ms. In contrast, PSI wafers show regions with effective lifetimes of 4.5 ms, even without gettering. This lifetime value is a factor of four larger than lifetimes of Cz wafers which are typically employed in today's PERC solar cells. We model the lifetime measurements with three Shockley-Read-Hall (SRH) defects: two defects that exist in the PSI and in the epi-ready wafer and a third defect that is only present in the epi-ready wafer.

KW - Epitaxy

KW - minority carrier lifetime

KW - porous silicon (PSI)

UR - http://www.scopus.com/inward/record.url?scp=85010223144&partnerID=8YFLogxK

U2 - 10.1109/JPHOTOV.2016.2642640

DO - 10.1109/JPHOTOV.2016.2642640

M3 - Article

AN - SCOPUS:85010223144

VL - 7

SP - 430

EP - 436

JO - IEEE Journal of Photovoltaics

JF - IEEE Journal of Photovoltaics

SN - 2156-3381

IS - 2

M1 - 7828018

ER -