The role of Schottky barrier in the resistive switching of SrTiO3: direct experimental evidence

Single crystalline SrTiO3 doped with 0.1 wt% Nb was used as a model system to evaluate the role of the Schottky barrier in the resistive switching of perovskites. The Ti bottom electrode formed an ohmic contact in the Ni/Nb: SrTiO3/Ti stack, whereas the Ni top electrode created a strong Schottky barrier, which was reflected in a huge semi-circle in the impedance spectrum of the stack. Bipolar switching was achieved in the voltage range of -4 to 4 V for the stack, two clear resistance states were created by electric pulses, and the Schottky barrier heights corresponding to the high/low resistance states were experimentally determined. A direct relationship between the resistance state and the Schottky barrier height was thus established.