Fig. 4

a A normalized read current at 25 °C sampled at a rate of 500 Hz in a RRAM cell that had gone through 10 cycles. This shows that RTN causes time-variant read current. b Shows the plot of normalized current in 1kbit array that had gone through 10 cycles, sampled at simultaneously at t1 = 3, t2 = 7.5, t3 = 14, and t4 = 17.5 s, sequentially. By comparing the snapshot at different time, read current fluctuates under the same read conditions