Effects of the electroforming polarity on bipolar resistive switching characteristics of SrTiO3-δ films

Department of Materials Science and Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
Applied Physics Letters (Impact Factor: 3.3). 10/2010; 97(11):112101 - 112101-3. DOI: 10.1063/1.3488810
Source: IEEE Xplore


The effects of the electroforming polarity on the bipolar resistive switching characteristics in SrTiO 3-δ thin films have been investigated. The conduction mechanisms of high resistance state and low resistance state are Poole–Frenkel emission and tunneling, respectively. The temperature dependences of the resistance at high and low resistance state are both semiconductorlike. The impact of the polarity of the electroforming voltage on the resistive switching mechanism and the distribution of defects was discussed. A simple model describing the combination of bulk and the interface effect was proposed to explain the resistive switching in this material.

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    ABSTRACT: We have demonstrated that the resistance switching (RS) effect can be controlled by the modification of the electrode configurations and the carrier densities in the Ag/SrTiO3 and Ag/Nb-doped SrTiO3(Nb:STO) structures. The elimination of the Schottky junction in the metal/Nb:STO completely destroys the RS effect, which suggests that the RS effect originates from the modification of Schottky-like barrier formed at the interface of metal/Nb:STO. The rectifying I-V curves revealed that the change in resistance was attributed to the trapping or detrapping carriers at the interface. The carrier density plays an important role in the determination of RS effect. The presence of the RS in SrTiO3 requires an appropriate doping level to provide conditions for trapping carriers at the interface.
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    ABSTRACT: Reversible and controllable conversion between unipolar and bipolar resistive switching (URS and BRS) was observed in Pt/TiO2/Pt memory devices. The URS and BRS of this device exhibited different low resistance states but shared the same high resistance state. The conduction mechanisms of low resistance states in URS and BRS are Ohmic conduction and electrons tunneling, respectively, while the high resistance state is controlled by Schottky barrier formed at the top interface of Pt/TiO2. The temperature dependence of resistance states indicates Magnéli phase filaments formed in URS. A unified model was then proposed to demonstrate the unification of filament and interfacial switching mechanisms.
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