Influences of Interface States on Resistive Switching Properties of TiO_x with Different Electrodes

Different TiO_x thin films prepared by graded or sufficient oxidization of Ti are applied with Pt or Ag electrode in metal−insulator-metal (MIM) structures for studying the properties and mechanisms of resistive switching. The differences on the mobile oxygen vacancies in TiO_x films and different work functions of the electrode films result in different insulator-metal interface states, which are displayed as ohmic-like or non-ohmic contact. Based on the interface states, the electrical models for MIM devices are analyzed and extracted. The electrode-limited effect and the bulk-limited effect can be unified to explain the mechanisms for resistive switching behavior as the dominant effect respectively in various conditions. All the current-voltage curves of the four kinds of specimens measured in the experiments can be explained and proved in accordance with the theory.