Large persistent photoconductivity in strontium titanate single crystals

摘要

Strontium titanate is a complex oxide with a range of interesting properties. Annealed samples show persistent photoconductivity at room temperature. When irradiated with sub-gap light, the resistivity drops significantly. The increased conductivity persists for days with negligible decay. This unusual effect is attributed to the excitation of an electron from an acceptor defect into the conduction band. A large barrier for recapture prevents electrons from returning to the defect level. Recent work suggests that optimized annealing conditions result in weakly p-type material prior to illumination.