Reversible alternation between bipolar and unipolar resistive switching in Ag/MoS2/Au structure for multilevel flexible memory

Reversible alternation between bipolar and unipolar resistive switching (RS) modes was observed by controlling voltage-polarity in Ag/MoS2/Au memory on polyethylene terephthalate (PET) substrate. The temperature-dependent low-resistance-state and Raman measurement indicated that Ag and sulphur vacancy (Vs)-based conductive filaments (CFs) were responsible for these two RS modes. The two kinds of CFs had different responses under positive read voltages. Thus, a new operation scheme of multilevel memory was demonstrated in which multiple states were distinguished by CF composition rather than resistance values. The memory capacity of the cell could be further extended by adjustments in CFs’ size in each mode. The RS performance of the device did not degrade under bending conditions even over 104 bending cycles, which indicated good mechanical flexibility. The present Ag/MoS2/Au memory has promise for future high-density flexible information storage.