Efficient Si solar cells by low-temperature solid-phase epitaxy

Solid-phase epitaxial Si layers of uniform thickness have been grown at 400–500 °C by transport of Si atoms from an amorphous Si film through an Al film deposited on 〈100〉 single crystal or polycrystalline n-type Si substrates. The epitaxial Si layers are strongly p type due to Al doping, and good rectifying junctions are formed between these layers and the substrates. Solar cells with conversion efficiencies at AM1 of 10.4 and 8.5% have been fabricated on 〈100〉 Si and polycrystalline Si substrates, respectively, without the use of an antireflection coating or back-surface field structure.