Processing dependence of minority carrier lifetimes in multicrystalline silicon

Abstract

Multicrystalline silicon (mcSi) solar cell efficiency is primarily influenced by minority carrier lifetime of the material. Lifetimes in mcSi vary strongly during processing. Step by step monitoring has allowed identification of both beneficial and poor processing steps and lead to rapid improvements in cell efficiency. Phosphorous gettering significantly improves lifetimes in the mcSi substrates investigated, where effective lifetimes of 250 /spl mu/s in 1.5 /spl Omega/ cm mcSi have been observed. This has permitted the achievement of record open circuit voltages greater than 655 mV and efficiencies greater than 18% with 0.2 /spl Omega/ cm and 0.5 /spl Omega/ cm mcSi solar cells.