An rf bridge technique for contactless measurement of the carrier lifetime in silicon wafers

A contactless rf technique has been developed for measurement of the photoconductivity induced in silicon wafers by a flash of light from GaAs laser diodes. The carrier lifetime inferred from the photoconductivity decay correlates well with diffusion length measurements made on solar cells fabricated from the same wafers. The technique has been applied successfully to silicon whose resistivity is as low as 0.1 Ω cm and lifetime as short as 0.2 μs.