9 ms Carrier Lifetime in Kerfless Epitaxial Wafers by n-Type POLO Gettering.

The bulk lifetime of epitaxially grown silicon wafers increases significantly after phosphorous diffusion gettering. A strong diffusion is advantageous for gettering but is not ideal for highest solar cell efficiencies. We find that gettering with an n-type polycrystalline silicon on oxide (POLO) junction increases the bulk lifetime of epitaxial wafers from originally 2.3 to 4.3 ms to finally up to 8 ms at an injection level Δp = 1015 cm-3. This lifetime increase as large as for phosphorous-diffusion gettering. However, POLO junctions have a superior surface passivation when compared to diffused junctions. This offers a novel gettering process that not only increase the charge carrier lifetime of epitaxial wafers but can also be effectively integrated into a solar cell processes employing POLO junctions. [ABSTRACT FROM AUTHOR]