Switching mode of the RRAM devices. (a) I-V curves for unipolar (nonpolar) switching where the switching direction is independent on the polarity of the applied voltage and (b) bipolar switching. In bipolar switching, SET and RESET occur at opposite polarity bias.
Prakash et al. Nanoscale Research Letters 2013 8:418 doi:10.1186/1556-276X-8-418