Unipolar conductivity of SrTiO3 crystals with light-induced drop in electrical resistance

Abstract

This paper reports on the results of the experimental investigation of unipolar (diode) current–voltage characteristics of local regions in high-resistance SrTiO₃ crystals that experienced a light-induced drop in electrical resistance. This behavior has been explained by the influence exerted on the electrical conductivity by the irradiated region in the Schottky barrier of one of the contacts. The ideality factor of the Schottky barrier has been determined and the barrier height for a number of regions has been estimated from measurements of the forward branch of the current–voltage characteristics. An analysis of the specific features in the behavior of the reverse branch of the current–voltage characteristics has revealed that, in the SrTiO₃ crystals with p-type conductivity, the resistance switching occurs through a pure electronic mechanism, in contrast to models based on electrochemical processes, in particular, the migration of oxygen vacancies.