Roles of Schottky barrier and oxygen vacancies in the electroforming of SrTiO3

Single crystalline SrTiO3 was used as a model system to evaluate the roles of the Schottky barrier and oxygen vacancies in electroforming. An advantage of single crystalline SrTiO3 is that the electrochemical processes at intermediate temperatures have been thoroughly investigated. To take this advantage, the electroforming was performed at 200 °C and subsequently at 24 °C; an electrical stress of 4 × 103 V/cm, which was about two orders of magnitude lower than the electrical stress in previous works, decreased the cell resistance by orders of magnitude. After the electroforming, bipolar resistive switching was realized at 24 °C.