High carrier lifetimes measured in EFG silicon after phosphorous diffusion

Lifetimes above 300 μs have been measured on EFG silicon ribbon samples following a double-sided phosphorus diffusion using solid sources. An average lifetime of 131 μs was obtained for a batch of 11 EFG blanks (10×10 cm) after diffusion. The lifetimes were measured by photoconductivity decay with an inductively coupled conductivity probe. Large improvements in lifetime exceeding a factor of 10 were observed as a result of the phosphorus diffusion. Thermal annealing alone produced only a 20% increase in lifetime. Czochralski (Cz) and Silso silicon wafers were also studied for comparison. The Cz material, was found to have higher as-grown lifetimes than EFG material but lifetimes similar to the better EFG samples after diffusion