Tailoring resistive switching characteristics in WOx films using different metal electrodes

• Metal–WOx–metal ReRAM devices are fabricated by using a sputtering system.
• Reliable bi-polar resistive switching (RS) is observed.
• Electrode's electronegativity plays a key role in determining RS properties.

We have investigated the role of the metal/oxide junction interface on the resistive switching (RS) characteristics in WO3+x films. The WOx films are fabricated on Pt substrates by magnetron sputtering at room temperature. Top metal contact (Au or Al) is fabricated by using thermal evaporator. The thicknesses of WOx films and top electrodes are 1 μm and 200 nm, respectively. It has been found that the bi-polar RS direction is dependent on the choice of top metal electrode, Au or Al. The sample with a Au top electrode shows clockwise (CW) RS mode whilst the sample with a Al top electrode shows counter-clockwise (CCW) RS mode. The on/off ratio is 10 times for Au/WOx/Pt and 100 times for Al/WOx/Pt. The bi-polar RS modes are modeled in terms of the difference in the electronegativity of the top and bottom electrodes.