Persistent photoconductivity in sulfur-diffused silicon

A large persistent photoconductivity effect is found in single-crystal p-type bulk silicon covered by an n-type surface layer produced by a sulfur diffusion. Recombination of carriers is precluded by their spatial separation in the n-p junction. The photogenerated holes exceed the relatively few remaining acceptor-introduced holes at our measurement temperature of 45 K, while the corresponding electrons are captured at the sulphur donors.