Resistive switching properties of Hf_xZr_1−xO₂ thin films for flexible memory applications

The flexible unipolar resistive switching characteristics of Au/Ni/HZO/Au devices on Polyethylene terephthalate substrates have been investigated for the RRAM applications. The devices demonstrated a bistable and reproducible unipolar RS behavior with a high OFF/ON ratio about 10³, and the memory widow could be maintained in repetitive programming/erase at least 1000 cycles. The retention property has no degradation at 6.3 × 10⁴ seconds. The current–voltage characteristics of the HZO samples show that the Ohmic contact and space charge limited current are suggested to response for the low resistance state and high resistance state, respectively. Combined with the conductance mechanism, the resistive switching behaviors can be explained by the conductive filaments model. The RS mechanism is attributed to restore and rupture caused by the joule heating and the redox reaction induced by the external electron injection. The memory devices also show good mechanical flexibility. It is believed that the HZO-based memory device has great potential to be used in high performance, flexible memory applications.