Resistively switching oxides are promising materials for use in electronic applications such as nonvolatile memories, logic gates, and artificial synapses. This work presents the bipolar resistive switching (BRS) in YMnO/Nb:SrTiO pn-heterojunctions. A thermally driven electroforming process is required prior to the observed BRS. Results indicate that the BRS in YMnO/Nb:SrTiO originates from the combined effects of charge trapping and detrapping processes along with the electro-migration of charged point defects in the depletion layer of the pn-heterojunction. It is shown that the built-in voltage of the pn-heterojunctions can be tuned by the oxygen partial pressure during growth of the YMnO thin film and impacts the working parameters of the resistively switching cell. This study provides a guideline for material engineering of bipolar resistive switches based on pn-heterojunctions.

We report a unipolar, nonvolatile resistive switching in polycrystalline YMnO3 thin films grown by pulsed laser deposition and sandwiched between Au top and Ti/Pt bottom electrodes. The ratio of the resistance in the OFF and ON state is larger than 103. The observed phenomena can be attributed to the formation and rupture of conductive filaments within the multiferroic YMnO3 film. The generation of conductive paths under applied electric field is discussed in terms of the presence of grain boundaries and charged domain walls inherently formed in hexagonal YMnO3. Our findings suggest that engineering of the ferroelectric domains might be a promising route for designing and fabrication of novel resistive switching devices.

Low power consumption is crucial for the application of resistive random access memory. In this work, we present the bipolar resistive switching in an Ag/TiOF/Ti/Pt stack with extremely low switch-on voltage of 0.07 V. Operating current as low as 10 nA was also obtained by conductive atomic force microscopy. The highly defective TiOF layer was fabricated by plasma treatment using helium, oxygen, and carbon tetrafluoride orderly. During the electroforming process, AgF nanoparticles were formed due to the diffusion of Ag which reacted with the adsorbed F in the TiOF layer. These nanoparticles are of great importance to resistive switching performance because they are believed to be conductive phases and become part of the conducting path when the sample is switched to a low-resistance state.