Tailoring resistive switching characteristics in WOx films using different metal electrodes

We have investigated the role of the metal/oxide junction interface on the resistive switching (RS) characteristics in WO_3+x films. The WO_x 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 WO_x 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/WO_x/Pt and 100 times for Al/WO_x/Pt. The bi-polar RS modes are modeled in terms of the difference in the electronegativity of the top and bottom electrodes.