Stable bipolar resistive switching characteristics observed in 8 x 8Pt/NiN_x/Ti/TiN crossbar array structures for resistive random access memories

The stable bipolar resistive switching (BRS) characteristics in a 8 x 8 Nickel Nitride (NiN_x)-based 8 x 8 crossbar array (CBA) resistive switching memory (RRAM) are demonstrated in the active size of 10 x 10 μm². First, in order to optimize the BRS of NiN_x-based RRAM cells, we estimated the thickness dependence of NiN_x films in the 8 x 8 CRS structures in a range of 30, 40 and 50 nm. In this test, the optimum BRS phenomena was observed when employing 50-nm thick NiN_x films. Then, in the repetitive BRS operations for 10 RRAM cells to evaluate the voltage and current distributions, we observed the voltage vatiations of 1.06 V for reset and 2.6 V for set. Then, the current varitions of 0.1 × 10¹ ratio at LRS and 0.41 × 10¹ ratio at HRS were observed in positive bias region, while the current variations of 0.1 × 10¹ ratio at LRS and 0.49 × 10¹ ratio at HRS were happened in negative bias region, respectively. Further, in the retention test, we observed the stable data storage properties at both HRS and LRS for 3 × 10⁴ s at 25 °C and 85 °C, respectively.